Linode: docs note for py3 limitation and deprecated API (#44723)

* Add note that linode-python having no py3 support.

Closes https://github.com/ansible/ansible/issues/44695.

* Add note that the module uses the deprecated API.

lib/ansible/modules/cloud/linode/linode.py

@@ -151,6 +151,8 @@ requirements:
 author:
 - Vincent Viallet (@zbal)
 notes:
+  - Please note, linode-python does not have python 3 support.
+  - This module uses the now deprecated v3 of the Linode API.
   - C(LINODE_API_KEY) env variable can be used instead.
   - Please review U(https://www.linode.com/api/linode) for determining the required parameters.
 '''