chore: update readme

README.md

@@ -1,7 +1,24 @@
 # musickitjs-v3-types
 TypeScript Type Declarations for [MusicKit JS V3](https://js-cdn.music.apple.com/musickit/v3/docs/index.html?path=/story/introduction--page)
 
-## Docs only
-The below URL could be used in the future to auto-generate these types
+## Usage
+Install using
+```bash
+npm install --save-dev musickitjs-v3-types
+```
+Then, add
+```js
+import 'musickitjs-v3-types';
+```
+to every file where you need the global `MusicKit`.
+You can further use
+```js
+import MusicKitInstance from 'musickitjs-v3-types/MusicKitInstance';
+```
+to get access to the `MusicKitInstance` definitions only.
 
+
+<!-- 
+The below URL could be used in the future to auto-generate these types
 https://js-cdn.music.apple.com/musickit/v3/docs/iframe.html?viewMode=story&id=reference-javascript-musickit-instance--page
+-->