Remove language about being the "official" registry

[jandrieu]

As a decentralized technology, there is no organization that has the authority to maintain an official registry, meaning one that has some form of requirement for DID methods.

Importantly, registering in the W3C DID Spec Registry is not a requirement, nor should it be.

That means this registry is no more official than any other registry maintained by any other organization.

It's helpful to have a W3C Registry that lists information known to the W3C, but calling that "official" moves us too far towards centralizing an authority of legitimacy for DID methods.