docs: add basic usage info (nuxt-modules#1419)

README.md

@@ -12,6 +12,17 @@ This branch is WIP 👷
 
 If you would like to use the stable version, please see the [`main` branch](https://github.com/nuxt-community/i18n-module)
 
+## Usage
+
+1. Add the following line to the `dependencies` in `package.json`:
+
+  ```
+  "@nuxtjs/i18n": "npm:@nuxtjs/i18n-edge"
+  ```
+
+2. Run `yarn` or `npm install`.
+3. Follow documentation of the stable version https://i18n.nuxtjs.org/ but keep in mind that not all features are supported yet and some things might be broken.
+
 ## License
 
 [MIT License](./LICENSE) - Copyright (c) Nuxt Community