First stage of document style approach finished

Everything is completely untested yet.

Replaced several scripts with notes instead. Almost everything
is laid out in the README. install-arch.sh is gone.

Separate isopackages, mainpackages, and aurpackages without
arrays anymore.

Removed unnecessary configs in custom/root-image/etc.

Deleted iso-to-drive-mbr.sh because dd seems to work well enough.

The README has several TODOs and some things will need to be
added/changed as this new method is tested.