Updated Roadmap (markdown)

Roadmap.md

@@ -7,7 +7,7 @@ This page describes a prioritized backlog of new vcpkg feature work and completi
   - [ ] **Release date:** May 2020 (2020.05)
 - [ ] **Versioning support** 
   - [x] **Description:** Vcpkg will give you more flexibility by letting you specify the versions of libraries to install.
-  - [ ] **Specification/design document**: _Work in progress_
+  - [ ] **Specification/design document**: [Link to draft PR](https://github.com/microsoft/vcpkg/pull/11758)
   - [ ] **Release date:** June 2020 (2020.06)
 - [ ] **Manifest file support** 
   - [x] **Description:** Vcpkg will support a manifest file that can specify all your dependencies declaratively and can be checked into source control.