Add a comment regarding forwarding and ipv6 blocking

dnscrypt-proxy/example-forwarding-rules.txt

@@ -10,5 +10,12 @@
 ## In order to enable this feature, the "forwarding_rules" property needs to
 ## be set to this file name inside the main configuration file.
 
+## Blocking IPv6 may prevent local devices from being discovered.
+## If this happens, set `block_ipv6` to `false` in the main config file.
+
+## Forward *.lan and *.local to 192.168.1.1
+# lan             192.168.1.1
+# local           192.168.1.1
+
 ## Forward queries for example.com and *.example.com to 9.9.9.9 and 8.8.8.8
 # example.com     9.9.9.9,8.8.8.8