Added style line to package.json, accepts @import

This is to make it much easier to load the CSS when using a import tool
like postcss-import, etc.

Author: MindTooth

package.json

@@ -3,7 +3,8 @@
   "description": "Touch enabled, responsive and fully customizable jQuery lightbox script",
   "version": "3.3.5",
   "homepage": "https://fancyapps.com/fancybox/3/",
-  "main": "./dist/jquery.fancybox.js",
+  "main": "dist/jquery.fancybox.js",
+  "style": "dist/jquery.fancybox.css",
   "author": "fancyApps",
   "license": "GPL-3.0",
   "repository": {