help: Document message actions menu on mobile.

help/message-actions.md

@@ -1,14 +1,40 @@
 # Message actions
 
-There are many ways to interact with a Zulip message.
+There are many ways to interact with a Zulip message. Here's an overview of the
+message actions in the web and desktop apps:
 
 ![Message actions](/static/images/help/message-actions.png)
 
+In the mobile app, the message actions menu lets you:
+
+- Add a [reaction](/help/emoji-reactions).
+- [Star](/help/star-a-message) the message.
+- [Quote](/help/quote-or-forward-a-message) the message.
+- [Copy message
+  content](/help/view-the-markdown-source-of-a-message#copy-message-content) in
+  Markdown, or [share
+  it](/help/view-the-markdown-source-of-a-message#share-message-content) to
+  other apps.
+- Copy a [link to the
+  message](/help/link-to-a-message-or-conversation#get-a-link-to-a-specific-message).
+
+## Open the message actions menu
+
+{start_tabs}
+
+{tab|desktop-web}
+
+{!message-actions-menu.md!}
+
+{tab|mobile}
+
+{!message-long-press-menu.md!}
+
+{end_tabs}
+
 ## Related articles
 * [User cards](/help/user-cards)
 * [Emoji reactions](/help/emoji-reactions)
+* [Star a message](/help/star-a-message)
 * [View a message's edit history](/help/view-a-messages-edit-history)
-* [Rename a topic](/help/rename-a-topic)
-* [Resolve a topic](/help/resolve-a-topic)
-* [Mute or unmute a topic](/help/mute-a-topic)
 * [Link to a message or conversation](/help/link-to-a-message-or-conversation)