Add links to Nanopass Framework

[rrnewton]

This is a great collection of resources!

I think one link to add would be to the "nanopass framework" for writing compilers in Scheme/Racket. It encapsulates various recursion schemes in a little macro-based DSL for compiler passes:

• https://nanopass.org/
• https://docs.racket-lang.org/nanopass/index.html
• https://dl.acm.org/citation.cfm?doid=2500365.2500618

Many students at Indiana University used it to write their compilers for class.
It's also what Chez Scheme is implemented in:

• https://github.com/cisco/ChezScheme

[passy]

This looks great. Do you want to add it in a PR? :)