text around self-signed certificates / excluding trust anchor not present in wallet attestation section

[jogu]

https://openid.net/specs/openid4vc-high-assurance-interoperability-profile-1_0.html#section-4.4.1 doesn't contain these two items:

1. The X.509 certificate of the trust anchor MUST NOT be included in the x5c JOSE header of the key attestation.
2. The X.509 certificate signing the key attestation MUST NOT be self-signed.

which I think we include everywhere else we mention the x5c Jose header. I think we probably intended these to be the case in this case too.