docs/devel/qapi-code-gen: Describe some doc markup pitfalls

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <20230427095346.1238913-1-armbru@redhat.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
1 file changed