Adds copilot instructions

[JPrevost]

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[coveralls]

Pull Request Test Coverage Report for Build 19641145314

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 97.833%

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Totals
Change from base Build 19640498490:	0.0%
Covered Lines:	948
Relevant Lines:	969

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💛 - Coveralls

[jazairi]

I like this as an addition to the first repo in which we've actively used Copilot. Having never written instructions like this, I don't have any immediate suggestions for improvement.

My main concern is that we will forget to update it over time. Maybe a section in the PR template is warranted?