[PR #5928/a64df658 backport][stable-6] Replace missing default favicon with docs.ansible.com favicon (#5935)

Replace missing default favicon with docs.ansible.com favicon (#5928)

* replace missing default favicon with docs.ansible.com

* create changelog fragment for PR 5928

* move changelog fragment

* fix parameter description

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

* fix parameter description

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

* add affected modules in changelog fragment

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

---------

Co-authored-by: Lars Krahl <lkr@mms-dresden.de>
Co-authored-by: Felix Fontein <felix@fontein.de>
(cherry picked from commit a64df658c5)

Co-authored-by: Lars Krahl <57526005+mmslkr@users.noreply.github.com>

plugins/modules/mattermost.py

@@ -60,8 +60,8 @@ options:
   icon_url:
     type: str
     description:
-      - Url for the message sender's icon.
-    default: https://www.ansible.com/favicon.ico
+      - URL for the message sender's icon.
+    default: https://docs.ansible.com/favicon.ico
   validate_certs:
     description:
       - If C(false), SSL certificates will not be validated. This should only be used
@@ -127,7 +127,7 @@ def main():
             text=dict(type='str'),
             channel=dict(type='str', default=None),
             username=dict(type='str', default='Ansible'),
-            icon_url=dict(type='str', default='https://www.ansible.com/favicon.ico'),
+            icon_url=dict(type='str', default='https://docs.ansible.com/favicon.ico'),
             validate_certs=dict(default=True, type='bool'),
             attachments=dict(type='list', elements='dict'),
         ),