Update Disconnect() comment

It looks like dgo has moved away from ChannelVoiceLeave ever since discord allows bot to connect to more than one channel. Confusing comment seeing that it is very hard to find information about the function that it mentions.

voice.go

@@ -135,7 +135,6 @@ func (v *VoiceConnection) ChangeChannel(channelID string, mute, deaf bool) (err
 
 // Disconnect disconnects from this voice channel and closes the websocket
 // and udp connections to Discord.
-// !!! NOTE !!! this function may be removed in favour of ChannelVoiceLeave
 func (v *VoiceConnection) Disconnect() (err error) {
 
 	// Send a OP4 with a nil channel to disconnect