chore(package): fixup browser field (#368)

Author: gkatsev

package.json

@@ -8,7 +8,7 @@
   },
   "main": "./cjs/index.js",
   "module": "es/index.js",
-  "browser": "dist/mux.js.js",
+  "browser": "dist/mux.js",
   "generator-videojs-plugin": {
     "version": "7.7.3"
   },