DOC: config: specify supported sections for "max-session-srv-conns"

There was no info about supported sections for "max-session-srv-conns"
proxy directive. A quick look at the code tells us that it may be used
in proxies with the FE capability set.

(cherry picked from commit 4039329954807769495fafd3c6c85e4407ba3a35)
Signed-off-by: Christopher Faulet <cfaulet@haproxy.com>
(cherry picked from commit 04445cf8a477bf9dc6c6490108c9645341002216)
Signed-off-by: Christopher Faulet <cfaulet@haproxy.com>
(cherry picked from commit 9003cded51329a8dea3292476daa2fcef2325bea)
Signed-off-by: Christopher Faulet <cfaulet@haproxy.com>
(cherry picked from commit 17056fbe51763c5f3144812bfff3853d906065ed)
Signed-off-by: Christopher Faulet <cfaulet@haproxy.com>
diff --git a/doc/configuration.txt b/doc/configuration.txt
index 46b8da7..8053307 100644
--- a/doc/configuration.txt
+++ b/doc/configuration.txt
@@ -8014,6 +8014,8 @@
   Set the maximum number of outgoing connections we can keep idling for a given
   client session. The default is 5 (it precisely equals MAX_SRV_LIST which is
   defined at build time).
+  May be used in sections :   defaults | frontend | listen | backend
+                                 yes   |    yes   |   yes  |   no
 
 maxconn <conns>
   Fix the maximum number of concurrent connections on a frontend