Update README.md

Author: openspeedtest

README.md

@@ -118,3 +118,23 @@ services:
             - '3001:3001'
         image: openspeedtest/latest
 ````
+## Advanced Configuration Options 
+
+- Container Port Configuration
+  
+To enable port changes, set the `CHANGE_CONTAINER_PORTS` environment variable to `"True"` and provide appropriate values for the following variables.
+
+`CHANGE_CONTAINER_PORTS=True`
+
+`HTTP_PORT=3000`
+
+`HTTPS_PORT=3001`
+
+- Set User
+  
+`SET_USER=101`
+
+- Only Allow `CORS Request` from listed domains. 
+
+`ALLOW_ONLY=domain1.com;domain2.com;domain3.com`
+