feat(locales): add Croatian translation (#4775)

packages/netlify-cms-locales/src/index.js

@@ -23,3 +23,4 @@ export { default as uk } from './uk';
 export { default as vi } from './vi';
 export { default as zh_Hant } from './zh_Hant';
 export { default as ko } from './ko';
+export { default as hr } from './hr';