update readme

Author: nadav867

README.md

@@ -88,7 +88,8 @@ The client build/static-files will be served with nginx server and will be expos
 
 #### Environment Variables
 
-Enviornment variables are located in `./client/.env` but can be declared into the dockerfile itself under ENV or in the docker compose file under enviornemt property
+Enviornment variables are located in `./client/.env` but can be declared into the dockerfile itself under ENV or in the docker compose file under enviornemt property.
+**In order to o use docker stack deploy** need one of the other options and not env_file.
 
 **note that nginx server has a minimalistic configuration**