Add small notes about deployments for multiple domains

deploy-to-docker-containers.md

@@ -86,6 +86,7 @@ docker  exec \
     acme.sh --deploy -d example.com  --deploy-hook docker
 ```
 
+**Note:** The environment variables are saved in the domain configuration. You can setup deployment for multiple domains by repeating the above command with different files, labels and reload commands.
 
 #### 5. All together, docker compose example:
 
@@ -115,6 +116,7 @@ services:
   
 ```
 
+**Note:** The environment variables are saved in the domain configuration. It is not necessary to keep them in the docker compose if the deploy commands above are used.
 
 ## 3. Deploy certs to a container in a remote docker host