SignalR authentication doesn't explain how to use both jwt and cookie authentication.

# Issue description

It took me a while to figure out how to do cookie website authentication and jwt bearer client authentication at the same time so that both web and .net SignalR client can connect. The least amount the docs can do is change the documentation to explain adding both authentication schemes on the SignalR hub:
```
[Authorize(AuthenticationSchemes = "Bearer, Identity.Application")]
```

The best the docs can do is fix the example SignalR Authentication project to be similar to [this](https://github.com/DanielRBowen/SignalRJwtAndCookieAuthentication)

# Software versions
.NET Core 3.0

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#### Document Details

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* ID: d0da2144-3730-f8ef-1d16-a89f11fd6198
* Version Independent ID: 6d8f5bc8-8f5c-ba13-b7f2-0366eac46f81
* Content: [Authentication and authorization in ASP.NET Core SignalR](https://docs.microsoft.com/en-us/aspnet/core/signalr/authn-and-authz?view=aspnetcore-3.0#feedback)
* Content Source: [aspnetcore/signalr/authn-and-authz.md](https://github.com/aspnet/AspNetCore.Docs/blob/master/aspnetcore/signalr/authn-and-authz.md)
* Product: **aspnet-core**
* Technology: **aspnetcore-signalr**
* GitHub Login: @bradygaster
* Microsoft Alias: **bradyg**