- phases.rst: add BootIso section, note on Buildinstall about the
alternative, update Createiso and ExtraIsos bootability descriptions
- configuration.rst: add Boot ISO Settings section with boot_iso_method,
boot_iso_skip, boot_iso_imagebuilder, and boot_iso_kiwi options;
update disc_types and Extra ISOs references
- phases.yaml: add BootIso to the essentials parallel group
- phases.svg: regenerated from updated phases.yaml
Signed-off-by: Simon de Vlieger <cmdr@supakeen.com>