Create sr-RS.yml

Serbian Cyrillic
```yaml
not_saved:
  one: "1 грешка је спречила да %{resource} буде сачувано:"
  other: "%{count} грешака је спречило да %{resource} буде сачувано:"
  few:  *****
  many:  ******
```

translations of something like: 
 - a few errors prohibited this %{resource} from being saved:
 - many erros prohibited this %{resource} from being saved: