Add s3-specific instructions for copilot

[peterrsongg]

Description

This is a set of instructions for copilot that applies to any file changed in S3 (for s3 generation PRs)

Motivation and Context

This will help us catch breaking changes.

Testing

I followed the docs and also I took a look at Aspire and how they did it to make sure it applies to specific file paths and general folder structure:

https://github.com/dotnet/aspire/blob/main/.github/instructions/xmldoc.instructions.md

Screenshots (if appropriate)

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist

• My code follows the code style of this project
• My change requires a change to the documentation
• I have updated the documentation accordingly
• I have read the README document
• I have added tests to cover my changes
• All new and existing tests passed

License

• I confirm that this pull request can be released under the Apache 2 license

[Copilot]

Pull Request Overview

This PR adds Copilot-specific instructions for reviewing S3 generation pull requests. The document provides guidelines for reviewing code changes that convert custom S3 code to generated code in the AWS .NET SDK.

Key Changes

• Adds comprehensive documentation for S3 generation PR review process
• Explains the difference between custom and generated S3 code files
• Provides specific guidelines to identify breaking changes during S3 code generation

[GarrettBeatty]

can/should you move the existing instructions inside the same copilot instructions folder too to be consistent? and do we need to rename the existing instructions to copilot instructions general? or something like that. just want to make sure we follow some consistent pattern.

[GarrettBeatty]

the name of the file i think should follow https://docs.github.com/en/copilot/how-tos/configure-custom-instructions/add-repository-instructions#creating-custom-instructions

s3.instructions.md

[peterrsongg]

done.

[GarrettBeatty]

can/should you move the existing instructions inside the same copilot instructions folder too to be consistent? and do we need to rename the existing instructions to copilot instructions general? or something like that. just want to make sure we follow some consistent pattern.

actually nvrmind this. i just checked https://docs.github.com/en/copilot/how-tos/configure-custom-instructions/add-repository-instructions#creating-custom-instructions repo wide instructions i think should stay where they are

[peterrsongg]

can/should you move the existing instructions inside the same copilot instructions folder too to be consistent? and do we need to rename the existing instructions to copilot instructions general? or something like that. just want to make sure we follow some consistent pattern.

the Aspire repo left the default instructions in the root of the .github directory so I left it as such.

[boblodgett]

Approved to trial this but we shouldn't be adding temporary project specific instructions to main. Any potential adjustments to this prompt are also going to require additional PRs and reviews from two developers.