Minor tidy up

Author: ssx

README.md

@@ -22,7 +22,7 @@ development or production use.
 This project is licensed under an Apache 2.0 license which you can find within
 this repository in the [LICENSE file](https://github.com/ssx/docker-php-fpm/blob/master/LICENSE).
 
-## Feedback
+### Feedback
 
 If you have any feedback, comments or suggestions, please feel free to open an
 issue within the repository on [Github](https://github.com/ssx/docker-php-fpm).