chore(#2966): Add initial Copilot instructions

[bdfranck]

This PR adds initial instruction files for GitHub Copilot to use. Topics include...

• How our documentation pages are structured
• How we show the LTS version of documentation
• How we write commits and pull requests

I've created a test PR using these instruction files: GovAlta/ui-components#2801

These instruction files will guide Copilot in the ui-components-docs repo both locally and online. We can continue to update them as we learn.

I've kept the instructions brief to align with the guidelines:

The instructions you add to your custom instruction file(s) should be short, self-contained statements that provide Copilot with relevant information to help it work in this repository. Because the instructions are sent with every chat message, they should be broadly applicable to most requests you will make in the context of the repository.

Questions

• Am I missing any key instructions?
• Could I improve the clarity of any of my instructions?
• Are any of my instructions incorrect or anti-patterns?

How to test

1. Set up GitHub Copilot with your IDE of choice
2. Check that Copilot > Use Instructions Files is enabled in your IDE settings
3. Open Copilot chat
4. Switch to Agent mode
5. Prompt Copilot to work on a GitHub Issue.

If it works, you should see the instruction files in the list of references:

Additional reading

• https://docs.github.com/en/copilot/how-tos/configure-custom-instructions/add-repository-instructions#using-one-or-more-instructionsmd-files

[netlify]

✅ Deploy Preview for abgov-ui-component-docs ready!

Name	Link
🔨 Latest commit	8977e16
🔍 Latest deploy log	https://app.netlify.com/projects/abgov-ui-component-docs/deploys/689e1f8e97efcc0008fcc650
😎 Deploy Preview	https://deploy-preview-418--abgov-ui-component-docs.netlify.app
📱 Preview on mobile	Toggle QR Code... Use your smartphone camera to open QR code link.

---

To edit notification comments on pull requests, go to your Netlify project configuration.