Configure copilot instructions .md for this repo.

[wadepickett]

Add repo custom instructions for GitHub Copilot to improve how Copilot handles assigned issues and code review.

.github/copilot-instructions.md.

More info here: Adding repository custom instructions for GitHub Copilot - GitHub Docs

Follow in the footsteps of David Pine's work for aspire only more specific to ASP.NET Core and its repo:
docs-aspire/.github/copilot-instructions.md at main · dotnet/docs-aspire

---

Associated WorkItem - 476801