Update README

README.md

@@ -21,10 +21,13 @@ Rollux is a simple dice rolling bot for discord
 1. Build docker image with a tag
    Example: `docker build -t rollux .`
 
-2. Mount `/data` directory in container with your auth.json file
+2. Add authentication by either:
+   1. Mount `/data` directory in container with your auth.json file
+   2. Pass the environment variable `DISCORD_TOKEN` with your discord token
 
 ## Example docker-compose file:
 
+For auth.json method:
 ```
 version: '2'
 
@@ -34,3 +37,14 @@ services:
     volumes:
       - ./data:/data
 ```
+
+For environment variable:
+```
+version: '2'
+
+services:
+  rollux:
+    image: 'rollux'
+	environment:
+		- DISCORD_TOKEN={your token}
+```