chore: move banner image into the repo

Author: neilcampbell

README.md

@@ -1,5 +1,5 @@
 <div align="center">
-<a href="https://github.com/algorandfoundation/algokit-cli"><img src="https://ipfs.algonode.xyz/ipfs/QmZqt55wHXrZzhBihSVzXDvwp9rguvLAvFhUm1qJR6GYeQ" width=60%></a>
+<a href="https://github.com/algorandfoundation/algokit-cli"><img src="https://raw.githubusercontent.com/algorandfoundation/algokit-cli/main/docs/imgs/banner.png" width=60%></a>
 </div>
 
 <p align="center">