DOC: peers: clarify when entry expiration date is renewed.

This patch add some details to know which rules are updating
the expiration timer of an entry.

It also adds a comment to know how to fetch a value without renewing
this timer.

This patch addresses github issue #615

This patch should be backported on all still supported branches

(cherry picked from commit 423ed389ac04f586d62cc185ff3e022e171d0612)
Signed-off-by: Christopher Faulet <cfaulet@haproxy.com>
(cherry picked from commit 9e8f894cab2dca0611e65c51d79812d9f3ef7987)
Signed-off-by: Christopher Faulet <cfaulet@haproxy.com>
diff --git a/doc/configuration.txt b/doc/configuration.txt
index 0e58e01..09e382f 100644
--- a/doc/configuration.txt
+++ b/doc/configuration.txt
@@ -11349,13 +11349,16 @@
                       belonging to the same unique process.
 
     <expire>   defines the maximum duration of an entry in the table since it
-               was last created, refreshed or matched. The expiration delay is
+               was last created, refreshed using 'track-sc' or matched using
+               'stick match' or 'stick on' rule. The expiration delay is
                defined using the standard time format, similarly as the various
                timeouts. The maximum duration is slightly above 24 days. See
                section 2.5 for more information. If this delay is not specified,
                the session won't automatically expire, but older entries will
                be removed once full. Be sure not to use the "nopurge" parameter
                if not expiration delay is specified.
+               Note: 'table_*' converters performs lookups but won't update touch
+               expire since they don't require 'track-sc'.
 
     <srvkey>   specifies how each server is identified for the purposes of the
                stick table. The valid values are "name" and "addr". If "name" is