Update Messaging.md

doc/help/Messaging.md

@@ -36,3 +36,12 @@ Which sends a special mention notification to **alice** to check your message.
 To mention a teammate, press `@` and you should see a list of team members who can be messaged. You can either type their username or use the **Up** and **Down** arrow keys and then **ENTER** to select them to be mentioned. 
 
 You can configure how you'd like to be alerted about mentions of your username, your first name, your nickname, or other keywords from **Account Settings** > **Notifications** and you can set channel-specific preferences from **[Channel Name]** > **Notification Preferences** 
+
+## Messages Dropdown Menu
+
+The Messages Dropdown Menu contains additional actions you can perform on a message: 
+
+- **Reply:** Opens up the sidebar so you can reply to a message in a comment thread.
+- **Permalink:** Creates a link to the message. Sharing this link with other users in the channel lets them view the linked message in the Message Archives. 
+- **Delete:** Deletes the message so it is no longer visible. Team Administrators can also delete another user's message. 
+- **Edit:** Lets you edit a message.