Adds usage instructions to README

Adds a code snippet to the README demonstrating how to use the sql2migration command.
This provides users with a quick start guide to using the tool.

Author: bertugfahriozer

README.md

@@ -9,6 +9,8 @@ composer require yourvendor/sql-to-migration
 ```
 
 ## Useage
+```bash
 php spark sql2migration /path/to/database.sql
+```
 
 For details: [Documentation](docs.md)