Update README.md with new csb link

Author: steviecs

README.md

@@ -5,7 +5,7 @@
 
 A POC React component library for rendering skeleton states that automatically adapt to the shape of your UI layout while data is being fetched.
 
-Try it live in a sandbox by reloading the in-window browser: https://codesandbox.io/s/github/steviecs/react-fallback
+Try it live in a sandbox by reloading the in-window browser: https://codesandbox.io/s/react-fallback-demo-b36dft?file=/src/App.tsx
 
 ## Motivation