fix(app):add gulpfile for docs

gulpfile.js

@@ -0,0 +1,12 @@
+'use strict';
+/**
+ * Load the TypeScript compiler and then load the tasks from 'scripts/gulp'.
+ */
+const path = require('path');
+const gulpPath = path.join(__dirname, 'scripts/gulp');
+const tsconfigPath = path.join(gulpPath, 'tsconfig.json');
+const tsconfig = require(tsconfigPath);
+
+// Register TypeScript.
+require('ts-node').register({ project: tsconfigPath });
+require(path.join(gulpPath, 'gulpfile'));