Adds a javascript widget tutorial to the dev tiddlywiki edition (#7016)

* Initial widget tutorials extracted from https://btheado.github.io/tw-widget-tutorial/

* Fixes for refresh behavior change

editions/dev/tiddlers/javascript-widget-tutorial/donothing.js

@@ -0,0 +1,16 @@
+/*\
+
+Do nothing widget
+
+\*/
+(function(){
+
+/*jslint node: true, browser: true */
+/*global $tw: false */
+"use strict";
+
+var Widget = require("$:/core/modules/widgets/widget.js").widget;
+
+exports.donothing = Widget;
+
+})();