docs: updated @discordjs/ws README.md to include optional packages (#8973)

* docs: updated ws's readme to include optional packages

- added optional packages to the README.md
- added an example on how to add a listener to the ws manager, in the README.md

* docs: changed "addEventListener" to "on" in ws's readme

changed "addEventListener" to "on" in @discord.js/ws README.md

Co-authored-by: kodiakhq[bot] <49736102+kodiakhq[bot]@users.noreply.github.com>

packages/ws/README.md

@@ -30,10 +30,16 @@ yarn add @discordjs/ws
 pnpm add @discordjs/ws
 ```
 
+### Optional packages
+
+- [zlib-sync](https://www.npmjs.com/package/zlib-sync) for WebSocket data compression and inflation (`npm install zlib-sync`)
+- [bufferutil](https://www.npmjs.com/package/bufferutil) for a much faster WebSocket connection (`npm install bufferutil`)
+- [utf-8-validate](https://www.npmjs.com/package/utf-8-validate) in combination with `bufferutil` for much faster WebSocket processing (`npm install utf-8-validate`)
+
 ## Example usage
 
 ```ts
-import { WebSocketManager } from '@discordjs/ws';
+import { WebSocketManager, WebSocketShardEvents } from '@discordjs/ws';
 import { REST } from '@discordjs/rest';
 
 const rest = new REST().setToken(process.env.DISCORD_TOKEN);
@@ -44,6 +50,10 @@ const manager = new WebSocketManager({
 	rest,
 });
 
+manager.on(WebSocketShardEvents.Dispatch, (event) => {
+	// Process gateway events here.
+});
+
 await manager.connect();
 ```