Update README.md [skip ci]

codegen-maven-plugin/README.md

@@ -63,6 +63,12 @@ To configure the plugin in your POM, the following is an example of the plugin d
 | `<className>`              | className              | String            | Required           | Class name of generated enum.                                                     |
 | `<inheritsFrom>`<br>&nbsp; | inheritsFrom<br>&nbsp; | String<br>&nbsp;  | Optional<br>&nbsp; | Interface class name the generated enum must inherit from.<br>**Default:** `null` |
 
+## Contributing
+
+Pull requests are welcome. For major changes, please open an issue first to discuss what you would like to change.
+
+Please make sure to update tests as appropriate.
+
 ### License
 
 This project is licensed under the MIT License - see the [LICENSE.txt](LICENSE.txt) file for details.