argument_spec is now better documented

plugins/module_utils/module.py

@@ -145,7 +145,12 @@ class AnsibleModule(object):
             doc = ""
         options = dict()
         help: _sdict
-        for option, help in cls.module_spec["argument_spec"].items():
+        specs = dict()
+        if "argument_spec" in cls._common_args:
+            specs.update(cls._common_args["argument_spec"])
+        if "argument_spec" in cls.module_spec:
+            specs.update(cls.module_spec["argument_spec"])
+        for option, help in specs.items():
             options[option] = dict(
                 type=help["type"],
             )