Add user-level custom agent configuration

[ashis-baral]

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/concepts/agents/copilot-cli/about-custom-agents#where-you-can-configure-custom-agents

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

The Where you can configure custom agents section currently documents three configuration levels:

• Repository level

• Organization level

• Enterprise level

Add the user level to this list.

For GitHub Copilot CLI, custom agents can also be configured in the user's home directory using:

$HOME/.copilot/agents/CUSTOM-AGENT-NAME.md

This provides user-level instructions that apply across repositories.

Additional information

A user-level agent is useful when a developer wants the same custom agent and instructions to be available across repositories without modifying each repository