docs: add community implementation of cache server (#10496)
### Description
Hola my good peeps from Turbo 👋
I'm just adding a little line here to the docs, linking a Turborepo
cache server implementation I built a little while ago.
[brunojppb/turbo-cache-server](https://github.com/brunojppb/turbo-cache-server)
is a Github Action that can be used throughout your workflows, only
requiring a S3-compatible storage.
Let me know. 🤝
