[PR #5962/51394b55 backport][stable-6] Add attributes to some messaging modules (#6060)

Add attributes to some messaging modules (#5962)

Add attributes to some messaging modules.

(cherry picked from commit 51394b55a0)

Co-authored-by: Felix Fontein <felix@fontein.de>

plugins/modules/mattermost.py

@@ -21,6 +21,13 @@ short_description: Send Mattermost notifications
 description:
     - Sends notifications to U(http://your.mattermost.url) via the Incoming WebHook integration.
 author: "Benjamin Jolivot (@bjolivot)"
+extends_documentation_fragment:
+    - community.general.attributes
+attributes:
+  check_mode:
+    support: full
+  diff_mode:
+    support: none
 options:
   url:
     type: str