Merge branch 'docs/document-broadcast-messages' into 'master'

Document broadcast messages in UI

Closes #45801

See merge request gitlab-org/gitlab-ce!24556

doc/administration/index.md

@@ -41,13 +41,14 @@ Learn how to install, configure, update, and maintain your GitLab instance.
 - [Polling](polling.md): Configure how often the GitLab UI polls for updates.
 - [GitLab Pages configuration](pages/index.md): Enable and configure GitLab Pages.
 - [GitLab Pages configuration for GitLab source installations](pages/source.md): Enable and configure GitLab Pages on
-[source installations](../install/installation.md#installation-from-source).
+  [source installations](../install/installation.md#installation-from-source).
 - [Environment variables](environment_variables.md): Supported environment variables that can be used to override their defaults values in order to configure GitLab.
 - [Plugins](plugins.md): With custom plugins, GitLab administrators can introduce custom integrations without modifying GitLab's source code.
 - [Enforcing Terms of Service](../user/admin_area/settings/terms.md)
 - [Third party offers](../user/admin_area/settings/third_party_offers.md)
 - [Compliance](compliance.md): A collection of features from across the application that you may configure to help ensure that your GitLab instance and DevOps workflow meet compliance standards.
 - [Diff limits](../user/admin_area/diff_limits.md): Configure the diff rendering size limits of branch comparison pages.
+- [Broadcast Messages](../user/admin_area/broadcast_messages.md): Send messages to GitLab users through the UI.
 
 #### Customizing GitLab's appearance
 
@@ -80,7 +81,7 @@ Learn how to install, configure, update, and maintain your GitLab instance.
 
 - [Mattermost](https://docs.gitlab.com/omnibus/gitlab-mattermost/): Integrate with [Mattermost](https://about.mattermost.com/), an open source, private cloud workplace for web messaging.
 - [PlantUML](integration/plantuml.md): Create simple diagrams in AsciiDoc and Markdown documents
-created in snippets, wikis, and repos.
+  created in snippets, wikis, and repos.
 - [Web terminals](integration/terminal.md): Provide terminal access to your applications deployed to Kubernetes from within GitLab's CI/CD [environments](../ci/environments.md#web-terminals).
 
 ## User settings and permissions

doc/user/admin_area/broadcast_messages.md

+# Broadcast Messages
+
+GitLab can display messages to all users of a GitLab instance in a banner that appears in the UI.
+
+![Broadcast Message](img/broadcast_messages.png)
+
+NOTE: **Note:**
+If more than one banner message is active at one time, they are displayed in a stack in order of creation.
+
+## Adding a broadcast message
+
+To display messages to users on your GitLab instance, add broadcast message.
+
+To add a broadcast message:
+
+1. Navigate to the **Admin Area > Messages** page.
+1. Add the text for the message to the **Message** field. Markdown and emoji are supported.
+1. If required, click the **Customize colors** link to edit the background color and font color of the message.
+1. Select a date for the message to start and end.
+1. Click the **Add broadcast message** button.
+
+NOTE: **Note:**
+Once a broadcast message has expired, it is no longer displayed in the UI but is still listed in the
+list of broadcast messages.
+
+## Editing a broadcast message
+
+If changes are required to a broadcast message, they can be edited.
+
+To edit a broadcast message:
+
+1. Navigate to the **Admin Area > Messages** page.
+1. From the list of broadcast messages, click the appropriate button to edit the message.
+1. After making the required changes, click the **Update broadcast message** button.
+
+TIP: **Tip:**
+Expired messages can be made active again by changing their end date.
+
+## Deleting a broadcast message
+
+Broadcast messages that are no longer required can be deleted.
+
+To delete a broadcast message:
+
+1. Navigate to the **Admin Area > Messages** page.
+1. From the list of broadcast messages, click the appropriate button to delete the message.
+
+Once deleted, the broadcast message is removed from the list of broadcast messages.
+
+NOTE: **Note:**
+Broadcast messages can be deleted while active.