add preAnswer and ringReady too

src/mod/applications/mod_httapi/docs/mod_httapi_doc.txt

@@ -237,6 +237,13 @@ ATTRS:
 is-conference       : true|false (set the conference flag for RFC4579 stuff.
 
 
+<preAnswer>
+		    : Establish media on the call without answering.
+
+<ringReady>
+		    : Indicate ringing to an unaswered channel.
+
+
 <hangup cause action>
 		    : Hangup the call