chore: add missing env vars to env.example

Author: geclos

.env.example

@@ -20,6 +20,8 @@ CACHE_PORT=6379
 CACHE_HOST=redis
 
 # Gateway Configuration
+GATEWAY_BIND_ADDRESS=localhost
+GATEWAY_BIND_PORT=8787
 GATEWAY_HOSTNAME=gateway # e.g gateway.latitude.so
 GATEWAY_PORT=8080
 GATEWAY_SSL=false