[Workflow] update documentation URL in readme

Author: xabbuh

README.md

@@ -4,7 +4,7 @@ Workflow Component
 Resources
 ---------
 
-  * [Documentation](https://symfony.com/doc/master/components/workflow.html)
+  * [Documentation](https://symfony.com/doc/current/components/workflow.html)
   * [Contributing](https://symfony.com/doc/current/contributing/index.html)
   * [Report issues](https://github.com/symfony/symfony/issues) and
     [send Pull Requests](https://github.com/symfony/symfony/pulls)