update readme for currently support version.

Author: Evan Lin

README.md

@@ -1,4 +1,8 @@
 # GoXmpp
 Make xmpp client more simple to use without complex setting.
 
+Currently this code works well if after jabberd2 2.2.17 w or w/o TLS . (include in Ubuntu 14.04 TLS).
+
+For 2.2.8(which Ubuntu 2.12.04 apt-get) it still has some issue
+
 Using mattn / go-xmpp but make setting more easier if you just install jabberd2 without any specific configuration.