Fix some typos.
Increment using the ++ operator.
Add a missing doc.
NewRootedArchive -> NewArchive.
buildArchiveRaw -> buildArchive.
Drop the extraneous "expected" parameter.
Make use of connInfo.Check().
Mention the single-source-of-truth for juju paths.
Add a backups abstraction.
Add Create() to the backups abstraction.
Add an API facade for backups.
Add tests.