DOC: http: add documentation for url32 and url32+src

This patch needs to be backported to 1.6 and 1.5.
(cherry picked from commit 0070cd52c86db832c771d43a21355df966a5ce2e)
(cherry picked from commit 00bddff7bae913cd634d8dad82604926aa83e363)
1 file changed