doc: updated link for running behind NAT

Author: limitedAtonement

env.example

@@ -48,7 +48,8 @@ TZ=UTC
 #PUBLIC_URL=https://meet.example.com
 
 # IP address of the Docker host
-# See the "Running behind NAT or on a LAN environment" section in the README
+# See the "Running behind NAT or on a LAN environment" section in the Handbook:
+# https://jitsi.github.io/handbook/docs/devops-guide/devops-guide-docker#running-behind-nat-or-on-a-lan-environment
 #DOCKER_HOST_ADDRESS=192.168.1.1
 
 # Control whether the lobby feature should be enabled or not