[webauthn] new commits pushed by vijaybh

The following commits were just pushed by vijaybh to 
https://github.com/w3c/webauthn:

* Make hashAlg a "recognized algorithm name". (#352)

* Make `hashAlg` a recognized algorithm name for a digest algorithm.

This drops the use of "S256", etc.

* Remove the IANA section for S256, etc.

This didn't really fit anyway since SHA-256, etc are digests not 
"Cryptographic
Algorithms for Digital Signatures and MACs".
  by Jeffrey Yasskin
https://github.com/w3c/webauthn/commit/c42a822a357c1697c999d930106ed666f78261c5