Document unix sockets with the session handler

Author: Nicolas

README.markdown

@@ -87,6 +87,7 @@ session.save_path = "tcp://host1:6379?weight=1, tcp://host2:6379?weight=2&timeou
 
 Sessions have a lifetime expressed in seconds and stored in the INI variable "session.gc_maxlifetime". You can change it with [`ini_set()`](http://php.net/ini_set).
 The session handler requires a version of Redis with the `SETEX` command (at least 2.0).
+phpredis can also connect to a unix domain socket: `session.save_path = "unix:///var/run/redis/redis.sock?persistent=1&weight=1&database=0`.
 
 
 ## Distributed Redis Array