Update url to markedjs (#601)

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* [x] Make sure you are merging your commits to `master` branch.
* [x] Add some descriptions and refer relative issues for you PR.
* [x] DO NOT include files inside `lib` directory.

Related: #410

This updates urls to marked github repo and documentation.

lib/docsify.js

@@ -610,7 +610,7 @@ var marked = createCommonjsModule(function (module, exports) {
 /**
  * marked - a markdown parser
  * Copyright (c) 2011-2014, Christopher Jeffrey. (MIT Licensed)
- * https://github.com/chjj/marked
+ * https://github.com/markedjs/marked
  */
 
 (function() {
@@ -1866,7 +1866,7 @@ function marked(src, opt, callback) {
     if (opt) { opt = merge({}, marked.defaults, opt); }
     return Parser.parse(Lexer.lex(src, opt), opt);
   } catch (e) {
-    e.message += '\nPlease report this to https://github.com/chjj/marked.';
+    e.message += '\nPlease report this to https://github.com/markedjs/marked.';
     if ((opt || marked.defaults).silent) {
       return '<p>An error occurred:</p><pre>'
         + escape(e.message + '', true)
@@ -3075,7 +3075,7 @@ Compiler.prototype._initRenderer = function _initRenderer () {
 
   /**
    * Render anchor tag
-   * @link https://github.com/chjj/marked#overriding-renderer-methods
+   * @link https://github.com/markedjs/marked#overriding-renderer-methods
    */
   origin.heading = renderer.heading = function (text, level) {
     var nextToc = {level: level, title: text};