docs: updates (#841)

docs/install/default_language.md

@@ -0,0 +1,36 @@
+# Default Language 🌍
+
+## How to change the default language
+
+- Open this file `client\src\store\language.js`
+- Modify the "default" in the lang variable with your ISO 3166 Alpha-2 code :
+
+Example: 
+from **English** as default
+
+```js
+import { atom } from 'recoil';
+
+const lang = atom({
+  key: 'lang',
+  default: 'en',
+});
+
+export default { lang };
+```
+
+to **Italian** as default 
+
+```js
+import { atom } from 'recoil';
+
+const lang = atom({
+  key: 'lang',
+  default: 'it',
+});
+
+export default { lang };
+```
+---
+ 
+### **If you wish to contribute your own translation to LibreChat, please refer to this document for instructions: [Contribute a Translation](../contributions/translation_contribution.md)**