talkatu/talkatu

Migrate to gi-docgen and remove the doc comments that were gtk-doc specific

Testing Done:
Build the docs locally and via the convey plan.

Reviewed at https://reviews.imfreedom.org/r/1056/
if get_option('vapi')
if not get_option('introspection')
error('Vala generation requires GObject Introspection.')
endif
add_languages('vala', native : false)
talkatu_vapi = gnome.generate_vapi('talkatu',
sources : talkatu_gir[0],
packages : [ 'gtk+-3.0' ],
install : true,
gir_dirs : meson.current_build_dir() / '..' / 'talkatu',
)
endif # vala