CreationOptions better understanding of parameters

[gppmad]

In the file src/webauthn/registration/types.d.ts it's better to enhance the documentation with more details present here: https://w3c.github.io/webauthn/#dom-publickeycredentialcreationoptions-challenge

Examples:

• BufferSource: dimension?
• PublicKeyCredentialUserEntity: there are some important thing to pay attention to. (To ensure secure operation, authentication and authorization decisions MUST be made on the basis of this id member, not the displayName nor name members. See Section 6.1 of [RFC8266].)