hidden field not needed in the edit page

[EDIT by guardrex to add the metadata. @TheEcMan, please use the **This page** feedback button+form at the bottom of any topic to open an issue. It will add the metadata automatically and ping the author.]

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not needed in the Pages/Courses/Edit.cshtml since it will be in the routed data during post

---
#### Document Details

⚠ *Do not edit this section. It is required for docs.microsoft.com ➟ GitHub issue linking.*

* ID: 140ce637-4d58-995f-c69e-b1de51f1dbb5
* Version Independent ID: 9bc46ffa-60db-bdee-0984-fab183c8f503
* Content: [Part 7, Razor Pages with EF Core in ASP.NET Core - Update Related Data](https://docs.microsoft.com/en-us/aspnet/core/data/ef-rp/update-related-data?view=aspnetcore-5.0)
* Content Source: [aspnetcore/data/ef-rp/update-related-data.md](https://github.com/dotnet/AspNetCore.Docs/blob/main/aspnetcore/data/ef-rp/update-related-data.md)
* Product: **aspnet-core**
* Technology: **aspnetcore-data**
* GitHub Login: @Rick-Anderson
* Microsoft Alias: **riande**