Update roadmap.md as .NET 5 had been released already (#6109)
Update roadmap.md as .NET 5 had been released already (#6109)

* Update roadmap.md as .NET 5 had been released already

* Update roadmap.md

Co-authored-by: Rahul Bhandari <03ae87ae0bcab5edc1782e9f6809704f2467c74a@microsoft.com>
dotnet/core