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/
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REPOSITORY = "talkatu/talkatu"
REPOSITORY_TYPE = "mercurial"
BRANCH = "default"
LAND_DEST_BRANCH = "default"
LAND_PUSH = False