Additional claims topic enhancements

Based on Q&A between community and engineering: https://github.com/dotnet/aspnetcore/issues/17905

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#### Document Details

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* ID: 64faf33b-2511-5e8f-c1b0-94f32dc07fa4
* Version Independent ID: 2697abc8-7727-2eba-74a5-fbbc8a7c80ff
* Content: [Persist additional claims and tokens from external providers in ASP.NET Core](https://docs.microsoft.com/en-us/aspnet/core/security/authentication/social/additional-claims?view=aspnetcore-3.1)
* Content Source: [aspnetcore/security/authentication/social/additional-claims.md](https://github.com/aspnet/AspNetCore.Docs/blob/master/aspnetcore/security/authentication/social/additional-claims.md)
* Product: **aspnet-core**
* Technology: **aspnetcore-security**
* GitHub Login: @guardrex
* Microsoft Alias: **riande**