docs: Add user guide for *Unsubscribe from a stream* feature

templates/zerver/help/index.md

@@ -93,7 +93,7 @@ as a “**realm**”.
 * Change the stream description
 * Rename a stream
 * Preview a stream (not implemented)
-* Unsubscribe from a stream
+* [Unsubscribe from a stream](/help/unsubscribe-stream)
 * Change who can join a stream
 * Pin a stream
 * [Change the color of a stream](/help/change-stream-color)

templates/zerver/help/unsubscribe-stream.md

@@ -0,0 +1,40 @@
+# Unsubscribe from a stream
+
+If you want to stop receiving messages from a particular stream in Zulip, you can choose to unsubscribe from that stream.
+
+There are two major ways to unsubscribe from a stream: unsubscribing from a stream through the stream browser and unsubscribing from a stream through the stream sidebar.
+
+## Unsubscribing from a stream through the stream browser
+If you want to unsubscribe from multiple streams at once, you should unsubscribe from streams through the stream browser.
+
+1. Click the cog (![cog](/static/images/help/cog.png)) next to
+**Streams** in the left sidebar. A tooltip labeled **Subscribe, add, or configure streams**
+will appear upon hovering above the cog.
+
+    ![Browse streams](/static/images/help/streams-1.png)
+2. The stream browser will now appear, showing all streams that you've subscribed to by default.
+
+    ![Streams Overview](/static/images/help/streams-overview.png)
+3. Locate the stream that you want to unsubscribe from in the stream browser. You can search for specific streams by entering the name of the stream in the **Filter streams** search box.
+
+    ![Filter streams box](/static/images/help/filter-stream.png)
+4. Move your cursor over the green checkmark to the left of the stream that you want to unsubscribe from and click it.
+
+    ![Unsubscribe before](/static/images/help/subscribe-after.png)
+5. The green checkmark should now disappear, confirming your unsubscription from the stream.
+
+    ![Unsubscribe after](/static/images/help/subscribe-before.png)
+
+## Unsubscribing from a stream through the stream sidebar
+
+If you want to quickly unsubscribe from a single stream, you can do so through the stream sidebar.
+
+1. In the left sidebar, located the **Streams** section. It shows all streams that you are currently subscribed to.
+
+    ![Left sidebar](/static/images/help/left-sidebar.png)
+2. Hover over the stream that you want to unsubscribe from in the left sidebar. The stream will be highlighted and a chevron (![chevron](/static/images/help/chevron.png)) will appear to the right of the stream.
+
+    ![Streams chevron](/static/images/help/unsubscribe-1.png)
+3. Click the chevron, then click the **Unsubscribe** option from the dropdown that appears. The stream will disappear from the left sidebar, confirming your unsubscription from the stream.
+
+    ![Stream dropdown](/static/images/help/unsubscribe-2.png)