Add note that if a DID Controller includes a proof on their DID Doc, they MUST add the implicit services

DIDDocs may have proofs, much as did:webvh has a proof in the DID Entry. When that happens, a did:webvh resolver should/must not alter the DIDDoc. That means the insertion of the implicit services (for files and whois) should not be done.

- At minimum, we should add guidance that the did:webvh DID Controller MUST put the implicit services into the DID Doc.
- Should we specify that if there is a `proof` item in the root of the DIDDoc, that the implicit services are NOT to be inserted into the DIDDoc?