CI improvements

[iolivia]

We have a CI thanks to @wbprice! 🎉

Some future improvements:

• use some clever caching to share state between the different folders
• automate the CI yml file to discover added/removed sample folders
• add mdbook build and test step - see https://rust-lang.github.io/mdBook/continuous-integration.html
• use clippy in the pipeline
• use prettier for the markdown files