update ms teams docs

microsoft-teams/installation.mdx

@@ -61,10 +61,14 @@ The Plain app must be added to a Team and channel that allows guests where you c
   Teams client
 </Warning>
 
-- Create a new Team
+- Create a new Team in your Teams instance
 - Create a new channel in the Team
 - Add the Plain app to the Channel (see below)
-- [Invite guests to the channel](https://support.microsoft.com/en-gb/office/add-guests-to-a-team-in-microsoft-teams-fccb4fa6-f864-4508-bdde-256e7384a14f)
+- [Invite guests to the channel as external guests](https://support.microsoft.com/en-gb/office/add-guests-to-a-team-in-microsoft-teams-fccb4fa6-f864-4508-bdde-256e7384a14f)
+
+<Warning>
+  You must be the owner of the channel you want to add the Plain app to, customers you are providing support to will be able to access this channel in your workspace. Currently, shared channels and B2B Direct connect channels are not supported.
+</Warning>
 
 Setting up the app: