Release Notes:
https://github.com/dotnet/core/blob/master/release-notes/3.0/3.0.0/3.0.0.md
What's new in .NET Core 3.0:
https://docs.microsoft.com/en-us/dotnet/core/whats-new/dotnet-core-3-0
(中文还没更新)
Downloads:
https://dotnet.microsoft.com/download/dotnet-core/3.0