qapi: Tidy up block-latency-histogram-set documentation some more

Commit a937b6aa739 (qapi: Reformat doc comments to conform to current
conventions) reflowed some text that should have been left alone.
Revert that.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-ID: <20240322140910.328840-4-armbru@redhat.com>
1 file changed