docs: Specify the override file
docs: Specify the override file

Even if it's empty (for now) it avoids make distcheck complaining

hsteinhaus/gst-rtsp-server,hsteinhaus/gst-rtsp-server,surround-io/gst-rtsp-server,thaytan/gst-rtsp-server,Lachann/gst-rtsp-server,Lachann/gst-rtsp-server,barisdemiray/gst-rtsp-server,barisdemiray/gst-rtsp-server,hsteinhaus/gst-rtsp-server,thaytan/gst-rtsp-server,thaytan/gst-rtsp-server,surround-io/gst-rtsp-server,Lachann/gst-rtsp-server,surround-io/gst-rtsp-server,barisdemiray/gst-rtsp-server