Update known-issues-limitations.md

Proposing known issue around guest users not being able to trigger flows in canvas apps.

Author: thomasjeffries11

powerapps-docs/teams/known-issues-limitations.md

@@ -122,5 +122,7 @@ Power Apps Studio and apps currently don't support **Dark theme**.
 
 -	It may take up to 15 minutes for new team users to be able to see the team within the Power Apps and Power Virtual Agents apps.
 
+- Users with the "Teams Guest" role cannot trigger flows embedded in Canvas Apps.
+
 
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