For #1998, Update conf

trunk/conf/full.conf

@@ -454,6 +454,7 @@ rtc_server {
     #       192.168.1.3 10.1.2.3 rtc.me # TODO: Implements it.
     # And by multiple ENV variables:
     #       $CANDIDATE $EIP # TODO: Implements it.
+    # @remark For Firefox, the candidate MUST be IP, MUST NOT be DNS name, see also https://github.com/ossrs/srs/pull/1998#issuecomment-726442999
     # default: *
     candidate       *;
     # The IP family filter for candidate, it can be: