set the channel topic: WireMock specifications working group: configuration files, Admin REST APIs, etc

FYI @Jamie Tanna [he/him] @Tom @mike waites specification WG placeholder, for all specs including the configuration files and admin REST APIs. Ideally, it would be great to align WireMock implementations overtime though the specs need to be extensible ◦ https://github.com/wiremock/ecosystem/issues/3 ◦ https://github.com/wiremock/ecosystem/issues/4