DOC: config: Explicitly list relaxing rules for accept-invalid-http-* options

DOC: config: Explicitly list relaxing rules for accept-invalid-http-* options

Time to time, new exceptions are added in the HTTP parsing (most of time H1)
to not reject some invalid messages sent by legacy applications. But the
documentation of accept-invalid-http-request and
accept-invalid-http-response options is not pretty clear. So, now, there is
an explicit list of relaxing rules for both options.

(cherry picked from commit 0f4fad5291027a7dfc8109fbbe2acd0bac8affd0)
Signed-off-by: Christopher Faulet <cfaulet@haproxy.com>