DOC: config: add matrix entry for "max-session-srv-conns"

Following 4039329 ("DOC: config: specify supported sections for
"max-session-srv-conns"), "max-session-srv-conns" was also missing
from the proxy keyword matrix.

(cherry picked from commit 8b2152181ccd81d75c57a49dfb0fb25c4ae52765)
Signed-off-by: Christopher Faulet <cfaulet@haproxy.com>
1 file changed