Update spec to be separate from implementation

[mistermoe]

Can you provide some context here @decentralgabe ?

[decentralgabe]

Idea was to have a clear specification defined for what features the SDK has - with links, descriptions, etc. This can be versioned.

separately we have an implementation report (test vectors, compliant sdks), with releases that comply with the spec versions.

[decentralgabe]

this is similar to how it's done in the w3c, e.g.:

• spec: https://w3c.github.io/vc-data-model/
• test suite: https://w3c.github.io/vc-data-model-2.0-test-suite/