[TASK] Use proper code formatting in the README (#595)

Author: oliverklee

README.md

@@ -792,7 +792,7 @@ classDiagram
 * [docteurklein](https://github.com/docteurklein) for output formatting and `CSSList->remove()` inspiration.
 * [nicolopignatelli](https://github.com/nicolopignatelli) for PSR-0 compatibility.
 * [diegoembarcadero](https://github.com/diegoembarcadero) for keyframe at-rule parsing.
-* [goetas](https://github.com/goetas) for @namespace at-rule support.
+* [goetas](https://github.com/goetas) for `@namespace` at-rule support.
 * [ziegenberg](https://github.com/ziegenberg) for general housekeeping and cleanup.
 * [View full list](https://github.com/sabberworm/PHP-CSS-Parser/contributors)