Update routing.md

[jz-k]

Updated language to clarify the purpose of Route constraint required. The phrase "non-parameter value" was awkward. The updated language clarifies that an explicit value is required, and I hope is less muddy. "Non-parameter value" gave me pause, since we are applying the attribute to a parameter.

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aspnetcore/fundamentals/routing.md	Routing in ASP.NET Core

[Copilot]

Pull request overview

Updates the routing documentation to clarify what the required route constraint does during URL generation, replacing the previously awkward “non-parameter value” phrasing.

Changes:

• Reworded the required route constraint description to emphasize needing an explicitly provided value during URL generation.
• Minor table row formatting alignment adjustments for the required, file, and nonfile rows.

[guardrex]

AI is correct to suggest updating the INCLUDE file (routing3-7.md) for prior versions with the change ...

Also, the <=7.0 content included from fundamentals/routing/includes/routing3-7.md still uses the old “non-parameter value” phrasing for the required constraint; updating that include would keep the guidance consistent across monikers.

I recommend adding a commit to update it to match ...

Enforces that an explicit value (not an ambient value) is present during URL generation.

[guardrex]

Thanks for this, @jz-k! Please make the recommended updates, and I'll ping Tom for a final review before we merge this.

[guardrex]

Thanks @jz-k ... Please sign the CLA ☝️ if you agree with its terms. We can't accept a PR unless the CLA is reviewed and signed.

[jz-k]

@dotnet-policy-service agree

[guardrex]

@cmastr ... The CLA flagging has been broken like this for years ... really as long as I can remember. The CLA notice often appears well after the PR has been submitted and after the dev and our team has had interaction on it, even with additional commits arriving. We were told at the outset not to even look at the content of a PR without a signed CLA, but that's impossible with the CLA notice popping up so late.

[tdykstra]

Thank you! The revised language is much better than the original.

Approved by tdykstra.