Update README.md

Author: imp-dance

README.md

@@ -7,7 +7,7 @@
 
 Lets you create loaders that contain multiple RTK queries.
 
-[Live demo / Playground](https://stackblitz.com/edit/react-ts-bwcrzm)
+[Live demo / Playground](https://codesandbox.io/s/rtk-query-loader-demo-42tubp)
 
 ## **Usage**