Update Redmine docs to let user know that `new_issue_url` is not being used.

doc/user/project/integrations/redmine.md

@@ -10,12 +10,7 @@ in the table below.
     | `description`   | A name for the issue tracker (to differentiate between instances, for example) |
     | `project_url`   | The URL to the project in Redmine which is being linked to this GitLab project |
     | `issues_url`    | The URL to the issue in Redmine project that is linked to this GitLab project. Note that the `issues_url` requires `:id` in the URL. This ID is used by GitLab as a placeholder to replace the issue number. |
-    | `new_issue_url` | This is the URL to create a new issue in Redmine for the project linked to this GitLab project |
-
-    Once you have configured and enabled Redmine:
-    - the **Issues** link on the GitLab project pages takes you to the appropriate
-      Redmine issue index
-    - clicking **New issue** on the project dashboard creates a new Redmine issue
+    | `new_issue_url` | This is the URL to create a new issue in Redmine for the project linked to this GitLab project. **This is currently not being used and will be removed in a future release.** |
 
     As an example, below is a configuration for a project named gitlab-ci.