Drop the arguments from the install examples to keep the commands easier
to read. Arguments to be introduced under "usage".
Signed-off-by: Simon de Vlieger <supakeen@redhat.com>
Supply initial documentation for `image-builder`. This documentation
will be imported into the osbuild [1] website.
[1]: https://osbuild.org/
Signed-off-by: Simon de Vlieger <supakeen@redhat.com>