feat: add translation support (#2870)

* feat: add translation support

* test(cypress): fix locale import

* docs: add locale documentation

* feat: add german translation (#2877)

* fix: locales package version, register all locales in netlify-cms

packages/netlify-cms/src/index.js

@@ -2,6 +2,7 @@ import createReactClass from 'create-react-class';
 import React from 'react';
 import { NetlifyCmsApp as CMS } from 'netlify-cms-app/dist/esm';
 import './media-libraries';
+import './locales';
 
 /**
  * Load Netlify CMS automatically if `window.CMS_MANUAL_INIT` is set.

packages/netlify-cms/src/locales.js

@@ -0,0 +1,6 @@
+import { NetlifyCmsApp as CMS } from 'netlify-cms-app/dist/esm';
+import * as locales from 'netlify-cms-locales';
+
+Object.keys(locales).forEach(locale => {
+  CMS.registerLocale(locale, locales[locale]);
+});