Add default WARTHOG_APP_HOST

.env

@@ -25,8 +25,10 @@ GRAPHQL_SERVER_PORT=8081
 # Hydra indexer gateway GraphQL server port
 HYDRA_INDEXER_GATEWAY_PORT=4000
 
-# Default GraphQL server host. It is required by the query-node start script.
+# Default GraphQL server host. It is required during "query-node config:dev"
 GRAPHQL_SERVER_HOST=localhost
+# Default WARTHOG_APP_HOST. It is required during "query-node-root processor:start"
+WARTHOG_APP_HOST=localhost
 
 # Websocket RPC endpoint containers will use.
 JOYSTREAM_NODE_WS=ws://joystream-node:9944/