Fixed documentation and options to address new sanity tests

- https://docs.ansible.com/ansible/latest/dev_guide/testing_validate-modules.html

Signed-off-by: Hideki Saito <saito@fgrep.org>

meta/runtime.yml

@@ -1,2 +1,8 @@
 ---
 requires_ansible: '>=2.9'
+plugin_routing:
+  callback:
+    skippy:
+      deprecation:
+        removal_date: '2022-06-01'
+        warning_text: See the plugin documentation for more details