Update README for drush command policy

drush/Commands/README.md

@@ -2,5 +2,12 @@ Drush command policies  have been implemented to prevent the execution of  certa
 'sql:sync', and 'sql:drop' in production or other environment instances. 
 
 To apply these policies, two actions must be taken:
-- In the definition of the alias for the environment where you want these policies to be applied you have to add the parameter: "protected-instance: true"
+- In the definition of the alias (sites/default.site.yml) for the environment where you want these policies to be applied you have to add the parameter: "protected-instance: true". For example:
+    ```yaml
+    pro:
+      root: /var/www/html/example.prod  
+      uri: https://www.example.com
+      user: example
+      protected-instance: true
+    ```
 - On the server of the environment, copy the 'drush/Commands/drush.yml.dist' to the user's .drush folder of the user used for SSH connections to the server.