Using docker as a model, this update creates separate manpages
for each OSTree command, such that the main manpage is not
cluttered and the separate pages can provide more in-depth detail
and exanples that might be useful to a user. Each page includes
synopsis, description, example, and a list of options if needd.
This update also alphabetizes the usage error output for ostree
and ostree admin so that it matches the list on the manpage.
Giuseppe Scrivano
Matthew Barnes
Colin Walters
Anne LoVerso