Copilot-instructions improvements (tdykstra)

[wadepickett]

Improve GitHub Copilot agent issue and review handling for this repo.

Based on any extra instructions it had to be given in order to complete the work correctly, if it would apply more broadly, create a set of rules to add to either the main instruction file here:

AspNetCore.Docs/.github/copilot-instructions.md at main · dotnet/AspNetCore.Docs

Or consider sub-instruction file architecture where it makes sense.

This issue is the 2nd half of this additional one split between team members:
#35991

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Associated WorkItem - 490062

[wadepickett]

@tdykstra, since we are both working on improved copilot-instructions at the same time, I'm making an issue for tracking and crediting time for each of us. When we are both assigned to the same issue rather than one for us each, ADO only attributes the work to one person.

[wadepickett]

Fixed with PR #36136