DEVELOPERS: add an entry for gstreamer1-editing-services

Add an entry for the recently added gstreamer1-editing-services package for
Peter Seiderer.

Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

DEVELOPERS

@@ -1456,6 +1456,7 @@ F:	package/edid-decode/
 F:	package/ghostscript-fonts/
 F:	package/gstreamer1/gst1-interpipe/
 F:	package/gstreamer1/gst1-validate/
+F:	package/gstreamer1/gstreamer1-editing-services/
 F:	package/libevdev/
 F:	package/log4cplus/
 F:	package/postgresql/