Major documentation refactor
This tries to fill almost all of the gaps in current runner documentation.
cc @axil @tmaczukin
Fixes https://gitlab.com/gitlab-org/gitlab-ci-multi-runner/issues/994
Do not update/delete: Banner broadcast message test data
Do not update/delete: Notification broadcast message test data
This tries to fill almost all of the gaps in current runner documentation.
cc @axil @tmaczukin
Fixes https://gitlab.com/gitlab-org/gitlab-ci-multi-runner/issues/994