doc: Updates the copyright file, removes mention of files we are no l… (#697)
doc: Updates the copyright file, removes mention of files we are no l… (#697)

* doc: Updates the copyright file, removes mention of files we are no longer using or distributing.

jitsi/jitsi-videobridge,jitsi/jitsi-videobridge,jitsi/jitsi-videobridge,gpolitis/jitsi-videobridge,jitsi/jitsi-videobridge,jitsi/jitsi-videobridge,jitsi/jitsi-videobridge,jitsi/jitsi-videobridge,gpolitis/jitsi-videobridge,gpolitis/jitsi-videobridge