docs: add editPageLink in demo (#343)

Author: Charan167

docs/demo/src/content/tutorial/meta.md

@@ -2,5 +2,6 @@
 type: tutorial
 mainCommand: ['npm run dev', 'Starting http server']
 prepareCommands:
-  - ['npm install', 'Installing dependencies']
+- ['npm install', 'Installing dependencies']
+editPageLink: https://github.com/stackblitz/tutorialkit/blob/main/docs/demo/src/content/tutorial/${path}?plain=1
 ---