Text format

manual/manual.html

@@ -414,6 +414,10 @@ post</em> icon at the top right of the centre column.</p>
 <img src="manual-new-post.png" alt="New post screen" />
 <figcaption aria-hidden="true">New post screen</figcaption>
 </figure>
+<p>The format of the post should be plain text, without any html markup.
+Any URLs will be automatically linked, and you can use hashtags and
+emoji. Emojis can be added via their name with colon characters before
+and after.</p>
 <h2 id="post-scopes">Post scopes</h2>
 <p>Posts can have different scopes which provide some amount of privacy,
 or particular functions. To change the scope select the current one and