help: Update "Rename a stream".

- Updates page to follow current help center documentation patterns.
- Adds Markdown include `tip` to rename stream via stream settings.

help/include/stream-settings-general-tab-tip.md

@@ -0,0 +1,5 @@
+!!! tip ""
+
+    You can also hover over a stream in the left sidebar, click on the
+    **ellipsis** (<i class="zulip-icon zulip-icon-more-vertical"></i>), and
+    select **Stream settings** to access the **General** tab.

help/rename-a-stream.md

@@ -4,17 +4,21 @@
 
 {start_tabs}
 
+{tab|desktop-web}
+
 {relative|stream|all}
 
 1. Select a stream.
 
 {!select-stream-view-general.md!}
 
-1. Click the **pencil** (<i class="fa fa-pencil"></i>)
-   to the right of the stream name. Enter a new name.
+1. Click the **pencil** (<i class="fa fa-pencil"></i>) icon
+   to the right of the stream name, and enter a new stream name.
 
 {!save-changes.md!}
 
+{!stream-settings-general-tab-tip.md!}
+
 {end_tabs}
 
 {!automated-notice-stream-event.md!}