Update language to align with v2 resolutions

[OR13]

issuanceDate, validFrom, validUntil

[Sakurann]

we should agree that iat/exp of VC-JWT are validity of the VC-JWT signature and are different from ValifFrom/ValidUntil that are validity of the data in the Credential #39 (comment)

[OR13]

@Sakurann I agree they are different, I presented on this at TPAC.

Basically:

proof.created <=> iat
issuanceDate <=> nbf
expirationDate <=> exp

changing the name of the left hand side does not change the alignment of intention:

proof.created <=> iat
validFrom <=> nbf
validUntil <=> exp

[Sakurann]

I agree with

proof.created <=> iat

I dont with

validFrom <=> nbf
validUntil <=> exp

ValidFrom and validUntil should not be mapped to any JWT Claim and used as-is. and exp JWT Claim should be used for the JWS signature validity.

Please see my proposal in issue #4

[OR13]

@Sakurann

validFrom ~= issuanceDate
validUntil ~= expirationDate

See 1.1 production rules:

https://w3c.github.io/vc-jwt/#in-addition-to

These are the rules for 1.1...

We can of course change them or not implement a similar mapping for 2.0.

[OR13]

No longer needs, especially when #88 is merged