docs(examples): add server bundling example with rollup

Related: https://github.com/socketio/socket.io/issues/4329

examples/rollup-server-bundle/.gitignore

@@ -0,0 +1 @@
+bundle.js

examples/rollup-server-bundle/index.js

@@ -0,0 +1,3 @@
+import { Server } from "socket.io";
+
+new Server(0);

examples/rollup-server-bundle/package.json

@@ -0,0 +1,19 @@
+{
+  "name": "rollup-server-bundle",
+  "version": "0.0.1",
+  "description": "",
+  "main": "index.js",
+  "type": "module",
+  "author": "Damien Arrachequesne <damien.arrachequesne@gmail.com>",
+  "license": "ISC",
+  "scripts": {
+    "build": "rollup --config rollup.config.js"
+  },
+  "devDependencies": {
+    "@rollup/plugin-commonjs": "^21.0.3",
+    "@rollup/plugin-json": "^4.1.0",
+    "@rollup/plugin-node-resolve": "^13.1.3",
+    "rollup": "^2.70.1",
+    "socket.io": "^4.4.1"
+  }
+}

examples/rollup-server-bundle/rollup.config.js

@@ -0,0 +1,12 @@
+import resolve from "@rollup/plugin-node-resolve";
+import commonjs from "@rollup/plugin-commonjs";
+import json from "@rollup/plugin-json";
+
+export default {
+  input: "index.js",
+  output: {
+    file: "bundle.js",
+    format: "esm",
+  },
+  plugins: [resolve(), commonjs(), json({ compact: true })],
+};