Remove comment from query vault endpoint const once spec is updated

[DRK3]

the queryVaultEndpoint has this comment above it:

// TODO (#126): As of writing, the spec shows multiple, conflicting query endpoints.
// See: https://github.com/decentralized-identity/secure-data-store/issues/110.
// The endpoint listed below is the correct one (per the comment made by one of the spec contributors).
// This also matches the one used by Transmute's EDV implementation.

Once the spec is updated, the comment can be removed.