Update README.md

docker-login/README.md

@@ -9,6 +9,7 @@ Use this GitHub Action to [log in to a private container registry](https://docs.
     loginServer: '<login server>' # default: index.docker.io
     email: '<email id>'
 ```
+Refer to the action metadata file for details about all the inputs https://github.com/Azure/docker-login/blob/master/docker-login/action.yml
 
 ## You can build and push container registry by using the following example
 ```yaml