Add module field to package.json

package.json

@@ -11,6 +11,7 @@
     "website": "gulp website"
   },
   "typings": "./monaco.d.ts",
+  "module": "./esm/vs/editor/editor.main.js",
   "repository": {
     "type": "git",
     "url": "https://github.com/Microsoft/monaco-editor"