updated readme

Author: Ilya Sakovich

README.md

@@ -51,3 +51,4 @@ php artisan nova-lang:publish de,ru --force
 | Indonesian | id | completed | [dvlwj](https://github.com/dvlwj) |
 | Hungarian | hu | completed | [milli05](https://github.com/milli05) |
 | Danish | da | completed | [olivernybroe](https://github.com/olivernybroe) |
+| Serbian | sr | completed | [marjanovicsteva](https://github.com/marjanovicsteva) |