Add comments for RTC candidate.

trunk/conf/full.conf

@@ -325,6 +325,8 @@ rtc_server {
     #       eth0 eth1   Use network interface eth0 and eth1. # TODO: Implements it.
     # Also by IP or DNS names:
     #       192.168.1.3 10.1.2.3 rtc.me # TODO: Implements it.
+    # And by multiple ENV variables:
+    #       $CANDIDATE $EIP # TODO: Implements it.
     # default: *
     candidate       *;
 }