docs: Add user guide for rename a stream

templates/zerver/help/index.md

@@ -91,7 +91,7 @@ as a “**realm**”.
 * The #announce stream
 * [Add or invite someone to a stream](/help/add-invite-stream)
 * Change the stream description
-* Rename a stream
+* [Rename a stream](/help/rename-stream)
 * Preview a stream (not implemented)
 * [Unsubscribe from a stream](/help/unsubscribe-stream)
 * Change who can join a stream

templates/zerver/help/rename-stream.md

@@ -0,0 +1,18 @@
+# Rename a Stream
+
+**Note:** This feature is only available to administrators.
+
+If you would like to change the name of an existing stream, locate the cog (![cog](/static/images/help/cog.png)) next to **Streams** in your left sidebar. A tooltip labeled **Subscribe, add, or configure streams** will appear.
+
+![Streams Cog](/static/images/help/streams-1.png)
+
+After clicking the cog, a modal with an overview of all existing streams will pop up.
+
+![Streams Overview](/static/images/help/streams-overview.png)
+
+To change the name of a stream, first click on the stream you want to change. After selecting a stream, a list of settings should appear in the right-hand panel under **Stream Settings.** Scroll down to **Administrator settings** to see the option to change the stream's name.
+
+![Stream Settings](/static/images/help/stream-settings-rename.png)
+
+Once the **Rename stream** field is selected, type in the new stream name. Your new stream name must be unique and no longer than 60 characters.
+If your stream name is valid, clicking the **Rename stream** button will save your changes.