DOC: typo: maxconn paragraph is wrong due to a wrong buffer size

HAProxy allocates 2 tune.bufsize, which is by default 16kB.

backport: 1.4 and above
(cherry picked from commit 79fb45d10bdf020a4f787424b73ca7dfb4fefa34)
(cherry picked from commit dc11ce58ebfe56be073f98528f45201107697ff9)
1 file changed