10.8k+ archived NIST documents w/ gov. shutdown

In short:

- https://csrc.nist.gov doesn’t serve its content anymore due to the US government shutdown.

- https://csrc.nist.rip is a mirror pulled from archive.org and https://csrc.nist.rip/library its searchable index.

Intended use case is to restore access to reference documents by replacing .gov by .rip.

I added the index for batch access and easy retrieval: for example, searching crystals gives the candidate implementations used during the Post-Quantum Cryptography Standardization process.