make the gobject introspection annotation nicer

[Stefan Kost <ensonic hora-obscura de>]

hi,

Indeed just appending the gobject introspection annotation keywords to
the end of the docs is not as nice as it could be. Finally the
complaints hit bugzilla:
https://bugzilla.gnome.org/show_bug.cgi?id=615860

Any ideas how we could present the extra information nicer?

Stefan