Update CREDITS.md

CREDITS.md

@@ -12,6 +12,8 @@ People are sorted by name so please keep this order.
 * [Amaury Carrade](https://github.com/AmauryCarrade): [contributions](https://github.com/FreshRSS/FreshRSS/commits?author=AmauryCarrade)
 * [ealdraed](https://github.com/ealdraed): [contributions](https://github.com/FreshRSS/FreshRSS/commits?author=ealdraed)
 * [Luc Didry](https://github.com/ldidry): [contributions](https://github.com/FreshRSS/FreshRSS/commits?author=ldidry)
+* [Marcus Rohrmoser](https://github.com/mro):
+[contributions](https://github.com/FreshRSS/FreshRSS/commits?author=mro)
 * [Marien Fressinaud](https://github.com/marienfressinaud): [contributions](https://github.com/FreshRSS/FreshRSS/commits?author=marienfressinaud), [Web](http://marienfressinaud.fr/)
 * [Melvyn Laïly](https://github.com/yaurthek): [contributions](https://github.com/FreshRSS/FreshRSS/commits?author=yaurthek)
 * [Nicolas Elie](https://github.com/nicolaselie): [contributions](https://github.com/FreshRSS/FreshRSS/commits?author=nicolaselie)