Update thread discussion docs (#80)

thread-discussions.mdx

@@ -11,6 +11,10 @@ To start a discussion you can either do it from within the thread in Plain or si
 We will then unfurl the link for you and populate the Plain thread context for your wider team to be aware of, without leaving Slack.
 For your convenience, the discussion will also be visible in the Plain thread.
 
+Any messages you or your team sends on the slack thread will show up in Plain, along with their reactions, mentions and attachments. You can respond either via Slack or directly through Plain.
+
+When a discussion is started, Plain will post a message with a "Resolve discussion" button. That can be used by anyone to signal that the discussion is concluded and the Plain thread will be moved back to Todo.
+
 To enable this functionality, you will need to setup your [Slack integration](/slack) and add the Plain bot to your channel.
 
 <Warning>
@@ -29,4 +33,4 @@ We will not start a discussion if:
 - the link is posted in a private channel Plain doesn't have access to.
 - the link is posted in a customer channel (typically _Slack Connect_), although you can always adjust this from your Slack settings.
 
-If you want to opt out of unfurling completely, you can disable thread discussions and link unfurling in your Slack integration settings.
+If you want to opt out completely, you can disable thread discussions and link unfurling in your Slack integration settings.