Add Distributed Tracing to the ASP.NET Core Documentation

The [Laravel docs have a section on Distributed Tracing](https://docs.sentry.io/platforms/php/guides/laravel/performance/distributed-tracing/) that explains what people need to do in the front end of their app to pass a propagation id through to the back end and trace between processes.

We should add something similar explaining what to do in a Razor template or something to the [ASP.NET Core docs](https://docs.sentry.io/platforms/dotnet/guides/aspnetcore/performance/).

[Originally raised on Discord](https://discord.com/channels/621778831602221064/621783515423440927/1184579464995287080).