Update text about work item and test instance

Author: peacekeeper

README.md

@@ -2,11 +2,11 @@
 
 # Universal Resolver
 
-The Universal Resolver resolves Decentralized Identifiers (DIDs) across many different DID methods, based on the [W3C DID Core 1.0](https://www.w3.org/TR/did-core/) and [DID Resolution](https://w3c-ccg.github.io/did-resolution/) specifications.
+The Universal Resolver resolves Decentralized Identifiers (DIDs) across many different DID methods, based on the [W3C DID Core 1.0](https://www.w3.org/TR/did-core/) and [DID Resolution](https://w3c-ccg.github.io/did-resolution/) specifications. It is a work item of the [DIF Identifiers&Discovery Working Group](https://github.com/decentralized-identity/identifiers-discovery/).
 
 See this [blog post](https://medium.com/decentralized-identity/a-universal-resolver-for-self-sovereign-identifiers-48e6b4a5cc3c) and this [webinar](https://ssimeetup.org/did-resolution-given-did-how-do-retrieve-document-markus-sabadello-webinar-13/) for an introduction.
 
-See https://resolver.identity.foundation/ for a stable version or https://dev.uniresolver.io/ for a test instance of a Universal Resolver. See [Docker Hub](https://hub.docker.com/u/universalresolver) for images.
+See https://dev.uniresolver.io/ for a DIF-hosted instance of the Universal Resolver that can be used for testing purposes. See [Docker Hub](https://hub.docker.com/u/universalresolver) for images.
 
 ## Quick Start