kamailio.cfg: describe log levels

etc/kamailio.cfg

@@ -132,6 +132,7 @@ import_file "kamailio-local.cfg"
 
 ####### Global Parameters #########
 
+### LOG Levels: 3=DBG, 2=INFO, 1=NOTICE, 0=WARN, -1=ERR
 #!ifdef WITH_DEBUG
 debug=4
 log_stderror=yes