docs-rst: sphinxify 802.11 documentation

This is just a very basic conversion, I've split up the original
multi-book template, and also split up the multi-part mac80211
part in the original book; neither of those were handled by the
automatic pandoc conversion.

Fix errors that showed up, resulting in a much nicer rendering,
at least for the interface combinations documentation.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

Documentation/index.rst

@@ -17,6 +17,7 @@ Contents:
    driver-api/index
    media/index
    gpu/index
+   80211/index
 
 Indices and tables
 ==================