lfs: add the '{oid}' template keyword to '{lfs_files}'
The 'sha256:' prefix is skipped because this seems like the most convenient way
to consume it. Maybe we should also add a '{oid_type}' keyword? Then again,
that can be added in the future if a different algorithm is supported.
#require docutils gettext
$ $TESTDIR/check-gendoc zh_CN
checking for parse errors