Fix sha-256 hash algorithm case in examples (external attachment digests)

[Vladimir Dzhuvinov]

In the v12 spec the “alg” name appears in several examples as uppercase SHA-256.

According to the referenced IANA registry the name must be lowercase:

https://openid.bitbucket.io/eKYC-IDA/openid-connect-4-identity-assurance-1_0-master.html#hash_name_registry

[Kai Lehmann]

Correct casing of digest alg name in attachment examples

Close #1269

→ <<cset 8949f8510bd8>>

[Kai Lehmann]

Good catch! I created PR#93 to address this. Unfortunatelly, referencing the issue in the PR automatically closed this issue already despite the PR not having merged yet …

[Kai Lehmann]

PR Merged.