Move DVCS information to new page

The DVCS information is large enough that it needs to live in its
own page. Shift information, making as few changes as possible.

doc/integration/jira/dvcs.md

+---
+stage: Create
+group: Ecosystem
+info: To determine the technical writer assigned to the Stage/Group associated with this page, see https://about.gitlab.com/handbook/engineering/ux/technical-writing/#assignments
+---
+
+# Jira DVCS connector
+
+If you're using GitLab.com and Jira Cloud, use the
+[GitLab for Jira app](index.md#gitlab-for-jira-app) unless you have a specific need for the DVCS Connector.
+
+When configuring Jira DVCS Connector:
+
+- If you are using self-managed GitLab, make sure your GitLab instance is accessible by Jira.
+- If you're connecting to Jira Cloud, ensure your instance is accessible through the internet.
+- If you are using Jira Server, make sure your instance is accessible however your network is set up.
+
+## GitLab account configuration for DVCS
+
+NOTE:
+To ensure that regular user account maintenance doesn't impact your integration,
+create and use a single-purpose `jira` user in GitLab.
+
+1. In GitLab, create a new application to allow Jira to connect with your GitLab account.
+1. Sign in to the GitLab account that you want Jira to use to connect to GitLab.
+1. In the top-right corner, select your avatar.
+1. Select **Edit profile**.
+1. In the left sidebar, select **Applications**.
+1. In the **Name** field, enter a descriptive name for the integration, such as `Jira`.
+1. In the **Redirect URI** field, enter `https://<gitlab.example.com>/login/oauth/callback`,
+   replacing `<gitlab.example.com>` with your GitLab instance domain. For example, if you are using GitLab.com,
+   this would be `https://gitlab.com/login/oauth/callback`.
+
+   NOTE:
+   If using a GitLab version earlier than 11.3, the `Redirect URI` must be
+   `https://<gitlab.example.com>/-/jira/login/oauth/callback`. If you want Jira
+   to have access to all projects, GitLab recommends that an administrator create the
+   application.
+
+   ![GitLab application setup](img/jira_dev_panel_gl_setup_1.png)
+
+1. Check **API** in the **Scopes** section, and clear any other checkboxes.
+1. Click **Save application**. GitLab displays the generated **Application ID**
+   and **Secret** values. Copy these values, which you use in Jira.
+
+## Jira DVCS Connector setup
+
+If you're using GitLab.com and Jira Cloud, use the
+[GitLab for Jira app](index.md#gitlab-for-jira-app) unless you have a specific need for the DVCS Connector.
+
+1. Ensure you have completed the [GitLab configuration](#gitlab-account-configuration-for-dvcs).
+1. If you're using Jira Server, go to **Settings (gear) > Applications > DVCS accounts**.
+   If you're using Jira Cloud, go to **Settings (gear) > Products > DVCS accounts**.
+1. Click **Link GitHub Enterprise account** to start creating a new integration.
+   (We're pretending to be GitHub in this integration, until there's additional platform support in Jira.)
+1. Complete the form:
+
+1. Select **GitHub Enterprise** for the **Host** field.
+
+1. In the **Team or User Account** field, enter either:
+
+   - The relative path of a top-level GitLab group that you have access to.
+   - The relative path of your personal namespace.
+
+   ![Creation of Jira DVCS integration](img/jira_dev_panel_jira_setup_2.png)
+
+1. In the **Host URL** field, enter `https://<gitlab.example.com>/`,
+   replacing `<gitlab.example.com>` with your GitLab instance domain. For example, if you are using GitLab.com,
+   this would be `https://gitlab.com/`.
+
+   NOTE:
+   If using a GitLab version earlier than 11.3 the **Host URL** value should be `https://<gitlab.example.com>/-/jira`
+
+1. For the **Client ID** field, use the **Application ID** value from the previous section.
+
+1. For the **Client Secret** field, use the **Secret** value from the previous section.
+
+1. Ensure that the rest of the checkboxes are checked.
+
+1. Click **Add** to complete and create the integration.
+
+ Jira takes up to a few minutes to know about (import behind the scenes) all the commits and branches
+ for all the projects in the GitLab group you specified in the previous step. These are refreshed
+ every 60 minutes.
+
+ In the future, we plan on implementing real-time integration. If you need
+ to refresh the data manually, you can do this from the `Applications -> DVCS
+ accounts` screen where you initially set up the integration:
+
+ ![Refresh GitLab information in Jira](img/jira_dev_panel_manual_refresh.png)
+
+To connect additional GitLab projects from other GitLab top-level groups (or personal namespaces), repeat the previous
+steps with additional Jira DVCS accounts.
+
+Now that the integration is configured, read more about how to test and use it in [Usage](index.md#usage).
+
+## Troubleshooting your DVCS connection
+
+Refer to the items in this section if you're having problems with your DVCS connector.
+
+### Jira cannot access GitLab server
+
+```plaintext
+Error obtaining access token. Cannot access https://gitlab.example.com from Jira.
+```
+
+This error message is generated in Jira, after completing the **Add New Account**
+form and authorizing access. It indicates a connectivity issue from Jira to
+GitLab. No other error messages appear in any logs.
+
+If there was an issue with SSL/TLS, this error message is generated.
+
+- The [GitLab Jira integration](../../user/project/integrations/jira.md) requires GitLab to connect to Jira. Any
+  TLS issues that arise from a private certificate authority or self-signed
+  certificate [are resolved on the GitLab server](https://docs.gitlab.com/omnibus/settings/ssl.html#other-certificate-authorities),
+  as GitLab is the TLS client.
+- The Jira Development panel integration requires Jira to connect to GitLab, which
+  causes Jira to be the TLS client. If your GitLab server's certificate is not
+  issued by a public certificate authority, the Java Truststore on Jira's server
+  needs to have the appropriate certificate added to it (such as your organization's
+  root certificate).
+
+Refer to Atlassian's documentation and Atlassian Support for assistance setting up Jira correctly:
+
+- [Adding a certificate to the trust store](https://confluence.atlassian.com/kb/how-to-import-a-public-ssl-certificate-into-a-jvm-867025849.html).
+  - Simplest approach is to use [`keytool`](https://docs.oracle.com/javase/8/docs/technotes/tools/unix/keytool.html).
+  - Add additional roots to Java's default Truststore (`cacerts`) to allow Jira to
+    also trust public certificate authorities.
+  - If the integration stops working after upgrading Jira's Java runtime, this
+    might be because the `cacerts` Truststore got replaced.
+
+- [Troubleshooting connectivity up to and including TLS handshaking](https://confluence.atlassian.com/kb/unable-to-connect-to-ssl-services-due-to-pkix-path-building-failed-error-779355358.html),
+  using the a java class called `SSLPoke`.
+
+- Download the class from Atlassian's knowledge base to Jira's server, for example to `/tmp`.
+- Use the same Java runtime as Jira.
+- Pass all networking-related parameters that Jira is called with, such as proxy
+  settings or an alternative root Truststore (`-Djavax.net.ssl.trustStore`):
+
+```shell
+${JAVA_HOME}/bin/java -Djavax.net.ssl.trustStore=/var/atlassian/application-data/jira/cacerts -classpath /tmp SSLPoke gitlab.example.com 443
+```
+
+The message `Successfully connected` indicates a successful TLS handshake.
+
+If there are problems, the Java TLS library generates errors that you can
+look up for more detail.
+
+### Scope error when connecting Jira via DVCS
+
+```plaintext
+The requested scope is invalid, unknown, or malformed.
+```
+
+Potential resolutions:
+
+- Verify the URL shown in the browser after being redirected from Jira in step 5 of [Jira DVCS Connector Setup](#jira-dvcs-connector-setup) includes `scope=api` in the query string.
+- If `scope=api` is missing from the URL, return to [GitLab account configuration](#gitlab-account-configuration-for-dvcs) and ensure the application you created in step 1 has the `api` box checked under scopes.
+
+### Jira error adding account and no repositories listed
+
+```plaintext
+Error!
+Failed adding the account: [Error retrieving list of repositories]
+```
+
+This error message is generated in Jira after completing the **Add New Account**
+form in Jira and authorizing access. Attempting to click **Try Again** returns
+`Account is already integrated with JIRA.` The account is set up in the DVCS
+accounts view, but no repositories are listed.
+
+Potential resolutions:
+
+- If you're using GitLab versions 11.10-12.7, upgrade to GitLab 12.8.10 or later
+  to resolve an identified [issue](https://gitlab.com/gitlab-org/gitlab/-/issues/37012).
+- If you're using GitLab Free or GitLab Starter, be sure you're using
+  GitLab 13.4 or later.
+
+[Contact GitLab Support](https://about.gitlab.com/support/) if none of these reasons apply.
+
+### Fixing synchronization issues
+
+If Jira displays incorrect information (such as deleted branches), you may need to
+resynchronize the information. To do so:
+
+1. In Jira, go to **Jira Administration > Applications > DVCS accounts**.
+1. At the account (group or subgroup) level, Jira displays an option to
+   **Refresh repositories** in the `...` (ellipsis) menu.
+1. For each project, there's a sync button displayed next to the **last activity** date.
+   To perform a *soft resync*, click the button, or complete a *full sync* by shift clicking
+   the button. For more information, see
+   [Atlassian's documentation](https://support.atlassian.com/jira-cloud-administration/docs/synchronize-jira-cloud-to-bitbucket/).