Add license code to index.js, and line to LICENSE

extensions/markdown/LICENSE

@@ -1,6 +1,7 @@
 The MIT License (MIT)
 
 Copyright (c) Toby Zerner
+based on code Copyright (c) 2017-2018 GitHub, Inc.
 
 Permission is hereby granted, free of charge, to any person obtaining a copy
 of this software and associated documentation files (the "Software"), to deal

extensions/markdown/js/src/forum/index.js

@@ -1,3 +1,12 @@
+/*!
+ * Includes modified code from GitHub Markdown Toolbar Element
+ * https://github.com/github/markdown-toolbar-element/
+ *
+ * Original Copyright GitHub, Inc.
+ * Released under the MIT license
+ * https://github.com/github/markdown-toolbar-element/blob/master/LICENSE
+ */
+
 import { extend } from 'flarum/extend';
 import TextEditor from 'flarum/components/TextEditor';
 import MarkdownArea from 'mdarea';

extensions/markdown/js/src/forum/util/apply.js

@@ -1,4 +1,4 @@
-/*!
+/*
  * Original Copyright GitHub, Inc. Licensed under the MIT License.
  * See license text at https://github.com/github/markdown-toolbar-element/blob/master/LICENSE.
  */