link to CI service docs from tpa-rfc-8

policy/tpa-rfc-8-gitlab-ci-libvirt.md

@@ -71,3 +71,4 @@ This proposal is currently in the `draft` state.
 
  * [example of libvirt in the custom executor](https://docs.gitlab.com/runner/executors/custom_examples/libvirt.html)
  * [building a MacOS image for KVM](https://github.com/foxlet/macOS-Simple-KVM)
+ * [CI service documentation](https://gitlab.torproject.org/tpo/tpa/team/-/wikis/service/ci)