Signal that the copilot-setup-steps samples are illustrative, not copy-ready #45861

Code of Conduct

• I have read and agree to the GitHub Docs project's Code of Conduct

What article on docs.github.com is affected?

• https://docs.github.com/en/copilot/how-tos/copilot-on-github/customize-copilot/customize-cloud-agent/customize-the-agent-environment#customizing-copilots-development-environment-with-copilot-setup-steps
• https://docs.github.com/en/copilot/tutorials/cloud-agent/improve-a-project#2-check-for-an-environment-setup-file

What part(s) of the article would you like to see updated?

Follow-up to #42379, per @subatoi's suggestion there. #45823 generalized the copy around the sample; two things still work against the sample being read as illustrative rather than copy-ready.

1. The sample renders a copy button. It's fenced ```yaml copy, which per the contributing guide adds a copy-to-clipboard button — an affordance that invites exactly the verbatim copying the surrounding text now advises against. Dropping the copy annotation leaves the sample and its syntax highlighting intact.

2. The "Improve a project" tutorial generates the file from this article. Its step 2 prompt asks Copilot to create copilot-setup-steps.yml "using... the details that are given in [the reference article]", so the sample is reproduced in practice regardless of intent. Adding a line to that prompt about triggers steers the generated file directly.

The extract further down that tutorial also shows both push and pull_request, while the sentence above it only calls out the workflow_dispatch trigger and the job name — so trimming it keeps it consistent with the updated prompt.

Additional information

I have all three changes ready and will open a single PR referencing this issue.