Add live interactive Starklings link alongside GitHub repository

[Giri-Aayush]

Currently, the README only links to the GitHub repository for Starklings:

• Starklings - Interactive tutorial to get you up and running with Cairo v1 and Starknet.

There is now a live interactive web-based version of Starklings available at https://starklings.app/.

Proposed change:
Update the Starklings entry to include both the GitHub repository and the live interactive version:

• Starklings - Interactive tutorial to get you up and running with Cairo v1 and Starknet.
  • GitHub Repository
  • Live Interactive Version - also promoted at basecamp

This enhancement will provide users with both options: the ability to explore the source code and run Starklings locally via the GitHub repository, as well as the convenience of trying it out immediately through the web-based version.