Add an APIchanges entry for url_alloc() and url_connect()

Originally committed as revision 23705 to svn://svn.ffmpeg.org/ffmpeg/trunk

doc/APIchanges

@@ -12,6 +12,9 @@ libavutil:   2009-03-08
 
 API changes, most recent first:
 
+2010-06-22 - r23704 - lavf 52.70.0 - url_alloc(), url_connect()
+  Add url_alloc() and url_connect()
+
 2010-06-22 - r23702 - lavf 52.69.0 - av_register_protocol2
   Add av_register_protocol2(), deprecating av_register_protocol()