fix import path

Author: trusktr

Diff for: src/core/global-api.js

@@ -1,6 +1,6 @@
 import prism from 'prismjs';
 import { marked } from 'marked';
-import * as util from './util.js';
+import * as util from './util/index.js';
 import * as dom from './util/dom.js';
 import { Compiler } from './render/compiler.js';
 import { slugify } from './render/slugify.js';