docs: Add a missing xi:include to gdata-docs.xml
docs: Add a missing xi:include to gdata-docs.xml

Pecisk/libgdata-gtasks,pwithnall/libgdata,Pecisk/libgdata,Pecisk/libgdata,Distrotech/libgdata,Pecisk/libgdata-gtasks,Distrotech/libgdata,GNOME/libgdata,pwithnall/libgdata,Distrotech/libgdata,Pecisk/libgdata,Pecisk/libgdata-gtasks