Remove the /usr/lib/osbuild/{assemblers, stages}/osbuild dirs.
NB: Release 13 got skipped since it replaced aforementioned
directories with symlinks and that would have required a
%pretrans script. osbuild was adjusted to use a different
mechanism to locate the osbuild module inside the container
rendering the symlinks (or 'osbuild' directories) obsolete.
Specify the exact version in the 'python3-osbuild' requirement
to avoid the library and the main binary being out of sync.
Add osbuild-ostree sub-package with the necessary bits to create
OSTree based images.
Following changes:
- build and include man pages, this adds 'make' and
'python3-docutils' to the build requirements
- add NEWS.md file with the release notes
Minor whitespace cleanups and correction of the previous changelog
entry that had the wrong version number.
