help: Document the saved snippets compose box feature.

Fixes #33131.

help/saved-snippets.md

@@ -0,0 +1,82 @@
+# Saved snippets
+
+You can save snippets of message content, and quickly insert them into the
+message you're composing.
+
+## Insert a saved snippet
+
+{start_tabs}
+
+{!start-composing.md!}
+
+1. Click the **Insert saved snippet** (<i class="zulip-icon
+   zulip-icon-message-square-text"></i>) icon at the bottom of the compose box to
+   open the saved snippets menu.
+
+1.  Start typing to filter saved snippets by title. Select a saved snippet to
+    insert it into the compose box.
+
+!!! keyboard_tip ""
+
+    You can also use <kbd>Ctrl</kbd> + <kbd>'</kbd> to open the saved
+    snippets menu.
+
+{end_tabs}
+
+## Create a saved snippet
+
+{start_tabs}
+
+{!start-composing.md!}
+
+1. *(optional)* Write the text you'd like to use as save as a snippet in the
+   compose box. You can [preview](/help/preview-your-message-before-sending) what
+   it will look like once sent.
+
+1. Click the **Insert saved snippet** (<i class="zulip-icon
+   zulip-icon-message-square-text"></i>) icon at the bottom of the compose box to
+   open the saved snippets menu.
+
+1. Select **Create a new saved snippet**.
+
+1. Enter a **Title** for the saved snippet, which will be used for finding saved
+   snippets.
+
+1. Enter the **Content** you'd like to save as a snippet, or modify the content
+   from the compose box as needed.
+
+1. Click **Save**.
+
+!!! keyboard_tip ""
+
+    You can also use <kbd>Ctrl</kbd> + <kbd>'</kbd> to open the saved
+    snippets menu.
+
+{end_tabs}
+
+## Delete a saved snippet
+
+{start_tabs}
+
+{!start-composing.md!}
+
+1. Click the **Insert saved snippet** (<i class="zulip-icon
+   zulip-icon-message-square-text"></i>) icon at the bottom of the compose box to
+   open the saved snippets menu.
+
+1. Hover over the saved snippet you'd like to delete, and click the **Delete
+   snippet** (<i class="fa fa-trash-o"></i>) icon on the right.
+
+!!! keyboard_tip ""
+
+    You can also use <kbd>Ctrl</kbd> + <kbd>'</kbd> to open the saved
+    snippets menu.
+
+{end_tabs}
+
+## Related articles
+
+* [Message formatting](/help/format-your-message-using-markdown)
+* [Preview messages before sending](/help/preview-your-message-before-sending)
+* [Mastering the compose box](/help/mastering-the-compose-box)
+* [Keyboard shortcuts](/help/keyboard-shortcuts)