chore: update locales README

Author: antonreshetov

src/main/services/i18n/locales/README.md

@@ -3,4 +3,16 @@
 ## Add new Locales
   - Make a duplicate of the `en` folder, then rename it to the necessary [two-letter locale code](https://en.wikipedia.org/wiki/List_of_ISO_639-1_codes).
   - Translate each value in each of the files.
+  - Add new [option](https://github.com/massCodeIO/massCode/blob/master/src/renderer/components/preferences/LanguagePreferences.vue#L42) for language selector where the name of the language corresponds to the name of the folder
+
+```js
+...
+  // 'en' for label & value
+  {
+    label: i18n.t('preferences:language.en'),
+    value: 'en'
+  }
+...
+```
+
   - Make PR.