connection: add a commenting explaining why the reply to the pmuc-v1 disco reply
connection: add a commenting explaining why the reply to the pmuc-v1 disco reply

Signed-off-by: Jonny Lamb <3d1fb3642aaab2ff70e3392a5ab916bf99eed6a3@collabora.co.uk>

community-ssu/telepathy-gabble,community-ssu/telepathy-gabble,community-ssu/telepathy-gabble,community-ssu/telepathy-gabble