build(dist): add missing params in pcakage.json

Author: posva

package.json

@@ -2,7 +2,10 @@
   "name": "vuefire",
   "version": "2.0.0-alpha.0",
   "description": "Firestore bindings for Vue.js",
-  "main": "dist/vuefire.js",
+  "main": "dist/vuefire.common.js",
+  "module": "dist/vuefire.esm.js",
+  "unpkg": "dist/vuefire.js",
+  "browser": "dist/vuefire.js",
   "files": [
     "dist/**",
     "LICENSE",