docs: fix named parameters docs for endpoint routing

[AugustoRengel]

Description

Removes the example that incorrectly referenced named parameters for routef in the Giraffe.Routing module, since this feature is only supported when using Giraffe.EndpointRouting. It also adds a reference to the official sample.

How to test

Review the updated documentation and verify that the named parameter examples refer only to the Giraffe.EndpointRouting module.

Related issues

Fixes #704

[Copilot]

Pull request overview

This PR corrects the documentation for the routef handler by clarifying that named parameters (e.g., %i:petId) are only supported when using ASP.NET Core's Endpoint Routing module, not in standard Giraffe routing. This fixes issue #704 where users were attempting to use named parameters with standard routing and finding they didn't work.

Key changes:

• Removed the misleading named parameter example from the standard routef section
• Updated the format string description to focus only on format characters
• Added a clear "Named parameters" subsection explaining that this feature requires Endpoint Routing, with an example and reference to the official sample

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[64J0]

Looks good to me, thanks for the contribution @AugustoRengel! I'm adding some suggestions that improve the text IMHO, please check them when you have some time.

[AugustoRengel]

Thank you for the suggestions. They make sense to me, so I’ve committed them.

[64J0]

Thanks again for this contribution @AugustoRengel 🚀