qapi: Refill doc comments to conform to conventions

qapi: Refill doc comments to conform to conventions

Sweep the entire documentation again.  Last done in commit
209e64d9edf (qapi: Refill doc comments to conform to current
conventions).

To check the generated documentation does not change, I compared the
generated HTML before and after this commit with "wdiff -3".  Finds no
differences.  Comparing with diff is not useful, as the reflown
paragraphs are visible there.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-ID: <20240729065220.860163-1-armbru@redhat.com>
[Straightforward conflict with commit 442110bc6f3 resolved]