add sample config for mod_memcache

git-svn-id: http://svn.freeswitch.org/svn/freeswitch/trunk@12872 d0543943-73ff-0310-b7d9-9358b9ac24b2

conf/autoload_configs/memcache.conf.xml

+<configuration name="memcache.conf" description="memcache Configuration">
+  <settings>
+    <!-- comma sep list of servers: eg:  localhost,otherhost:port,anotherone -->
+    <param name="memcache-servers" value="localhost"/>
+  </settings>
+</configuration>