Update WebCrypto supported ciphersuites

[Frosne]

Problem:

Currently, the page mentions that WebCrypto supports (experimentally) 2,5,7.
I believe that WebCrypto now supports MLS_128_DHKEMX25519_AES128GCM_SHA256_Ed25519 as well.

It's a minor detail, but I believe that there will be some users preferring X25519 to NIST curves.

(See also https://www.w3.org/TR/webcrypto/#x25519 and https://www.w3.org/TR/webcrypto/#ed25519)