docs: Remove superflous XML comments in doc string for GDBusProxyTypeFunc
docs: Remove superflous XML comments in doc string for GDBusProxyTypeFunc

https://bugzilla.gnome.org/show_bug.cgi?id=766899

endlessm/glib,johne53/MB3Glib,johne53/MB3Glib,johne53/MB3Glib,endlessm/glib,endlessm/glib,johne53/MB3Glib,endlessm/glib,johne53/MB3Glib,johne53/MB3Glib,endlessm/glib