help: Restructure /help/mute-a-topic.

- Create separate sections for muted vs. unmuted streams.
- Combine instructions for muting/unmuting topics.

Fixes #25311.

help/include/mute-unmute-intro.md

@@ -9,14 +9,15 @@ Muting has the following effects:
   word](/help/dm-mention-alert-notifications#alert-words) notifications), unless
   you are [mentioned](/help/mention-a-user-or-group).
 - Messages in muted topics do not appear in the [**All messages**
-  view](/help/all-messages).
+  view](/help/all-messages) or the mobile **Inbox** view.
 - Muted topics appear in the [**Recent conversations**
   view](/help/recent-conversations) only if the **Include muted** filter is
   enabled.
 - Unread messages in muted topics do not contribute to stream unread counts.
-- In the left sidebar, muted topics and streams are grayed out. They are also
-  sorted to the bottom of their stream (for topics) or stream section (for
-  streams).
+- Muted topics and streams are grayed out in the left sidebar of the desktop/web
+  app, and in the mobile app.
+- In the desktop/web app, muted topics are sorted to the bottom of their stream,
+  and muted streams are sorted to the bottom of their stream section.
 
 !!! warn ""
 

help/mute-a-topic.md

@@ -2,7 +2,7 @@
 
 {!mute-unmute-intro.md!}
 
-## Mute a topic
+## Configure topic notifications in unmuted streams
 
 {start_tabs}
 
@@ -10,7 +10,7 @@
 
 {!topic-actions.md!}
 
-1. Select **Mute topic**.
+1. Select **Mute topic** or **Unmute topic**.
 
 !!! tip ""
 
@@ -21,13 +21,13 @@
 
 {!topic-long-press-menu.md!}
 
-1. Tap **Mute topic**.
+1. Tap **Mute topic** or **Unmute topic**.
 
 {!topic-long-press-menu-tip.md!}
 
 {end_tabs}
 
-## Unmute a topic
+## Configure topic notifications in muted streams
 
 {start_tabs}
 
@@ -35,7 +35,7 @@
 
 {!topic-actions.md!}
 
-1. Select **Unmute topic**.
+1. Select **Unmute topic** or **Mute topic**.
 
 !!! tip ""
 
@@ -44,9 +44,19 @@
 
 {tab|mobile}
 
+1. Tap the **Streams**
+   (<img src="/static/images/help/mobile-hash-icon.svg" alt="hash" class="mobile-icon"/>)
+   tab at the bottom of the app.
+
+1. Select a grayed-out (muted) stream from the streams list.
+
+1. Tap the **Topics list**
+   (<img src="/static/images/help/mobile-list-icon.svg" alt="list" class="mobile-icon"/>)
+   icon in the upper right corner of the app.
+
 {!topic-long-press-menu.md!}
 
-1. Tap **Unmute topic**.
+1. Tap **Unmute topic** or **Mute topic**.
 
 {!topic-long-press-menu-tip.md!}