Merge branch 'mz/doc-notes-are-not-anchors'

Objects that lost references can be pruned away, even when they have notes attached to it (and these notes will become dangling, which in turn can be pruned with "git notes prune"). This has been clarified in the documentation. * mz/doc-notes-are-not-anchors: docs: clarify that refs/notes/ do not keep the attached objects alive