This patch fixes 3 minor issues in the microversion devref:
- ``# no qa`` is replaced with ``# noqa``
- Change example usage of api_version requiring noqa with preferred
method that doesn't.
- Replace api_version decorator in example with the full and correct
decorator wsgi.Controller.api_version.
TrivialFix
Change-Id: I31af4c566683cf5b38b74c9f9164fdc6aa0ee6c7