Update documentation for GitHub Actions runner context to include environment property

[maskati]

Select Topic Area

Bug

Body

The documentation for the runner context does not indicate a new property environment:

• Value is github-hosted for GitHub hosted runners
• Value is self-hosted for self-hosted runners

[jsoref]

You'll want to file this in https://github.com/github/docs/issues/new/choose

[maskati]

Thanks for the info, I created an issue in the correct repo.