- Move everything related to base/ into that directory, including Containerfile
- Introduce `bootc-base-image-rebuild-self` that can be used to
resynthesize the base image, and it has docs.
- Rework the standard image to put its build instructions in
usr/share/doc/bootc-image-standard to serve as a reference
Signed-off-by: Colin Walters <walters@verbum.org>