Document options validation source generator

[cremor]

Description

.NET 8 added an options validation source generator which should be documented. Issue dotnet/runtime#85475 and PR dotnet/runtime#87587

Related: #32544

Page URL

https://learn.microsoft.com/en-us/aspnet/core/fundamentals/configuration/options?view=aspnetcore-8.0

Content source URL

https://github.com/dotnet/AspNetCore.Docs/blob/main/aspnetcore/fundamentals/configuration/options.md

Document ID

dc7e3449-650b-d117-5eac-69e5ccb250cb

Article author

@Rick-Anderson

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Associated WorkItem - 253188

[Rick-Anderson]

Related #32544

@cremor unfortunately I won't have time to work on this until .NET 9 ships. Any chance you could draft the new content and I could help you finish it?

[cremor]

I haven't used the validation source generator myself yet, that's also why I'd like to have documentation for it. So I wouldn't be a good candidate to write that documentation.