Update docs links to 3.1 (#35309)

README.md

@@ -44,7 +44,7 @@ For other issues, please use the following repos:
 ## Useful Links
 
 * [.NET Core source index](https://source.dot.net) / [.NET Framework source index](https://referencesource.microsoft.com)
-* [API Reference docs](https://docs.microsoft.com/dotnet/api/?view=netcore-3.0)
+* [API Reference docs](https://docs.microsoft.com/dotnet/api/?view=netcore-3.1)
 * [.NET API Catalog](http://apisof.net) (incl. APIs from daily builds and API usage info)
 * [API docs writing guidelines](https://github.com/dotnet/dotnet-api-docs/wiki) - useful when writing /// comments
 
@@ -55,7 +55,7 @@ For other issues, please use the following repos:
 There are many .NET related projects on GitHub.
 
 - [.NET home repo](https://github.com/Microsoft/dotnet) - links to 100s of .NET projects, from Microsoft and the community.
-- [ASP.NET Core home](https://docs.microsoft.com/aspnet/core/?view=aspnetcore-3.0) - the best place to start learning about ASP.NET Core.
+- [ASP.NET Core home](https://docs.microsoft.com/aspnet/core/?view=aspnetcore-3.1) - the best place to start learning about ASP.NET Core.
 
 This project has adopted the code of conduct defined by the [Contributor Covenant](http://contributor-covenant.org/) to clarify expected behavior in our community. For more information, see the [.NET Foundation Code of Conduct](http://www.dotnetfoundation.org/code-of-conduct).