DOC: remove old tunnel mode assumptions

MichaƂ Pasierb reported doc inconsistencies regarding the old default
HTTP tunnel mode.

This patch fixes a few of those inconsistencies and should be backported
to both 1.6 and 1.5.
(cherry picked from commit f01a9cde382aa63423072b2666341aff8d7370ed)
(cherry picked from commit fc00724f37d753dc75cb9e8b5cf8628cf3dafe2b)
1 file changed