Merge pull request dotnet#5115 from dotnet/new

Update to 5.0.0-preview.8.md

Add missing downloads for SDK 2.0.0-preview (dotnet#4774)

There were entries for win/x86 and win/x64 named like non-installer packages,
but they pointed to the executable installers.
This corrects their name, and adds the correct links to the non-installer packages.

Merge pull request dotnet#4972 from dotnet/rbhanda-patch-1

Update 5.0.0-preview.7.md

Merge pull request dotnet#4940 from dotnet/rbhanda-patch-1

Update 2.1.20.md

Merge pull request dotnet#4940 from dotnet/rbhanda-patch-1

Update 2.1.20.md

Merge pull request dotnet#4874 from dotnet/rbhanda-patch-1

Update 5.0.0-preview.6.md

Update releases.json

correct preview.1 runtime version

Update releases.json

correct preview.1 runtime version

Update releases.json

correct preview.1 runtime version

Merge pull request dotnet#4682 from dotnet/rbhanda-patch-1

Update Release notes with Github Announcement for May release