[Fedora-spins] spin-kickstart package updates

[Bruno Wolff III]

I created updates for the F13 and master (to be F14) branches.
I requested a push to testing for the F13 update.

In the F14 branch I made a few changes that we can go over at one of the
spins meetings.

I added some build documentation to the top level readme file.

I removed redundant packaging of the top level doc files.

I made the README files in the subdirectories doc files.

I changed the custom kickstart files to use ../ when including other
kickstart files. This avoids having to package copies of some of the
base kickstart files. However custom-kkickstarts now requires
fedora-kickstarts.

I learned some stuff about developing branches with git, though next time
I'll probably clean some things up, since I left multiple commits to
fix problems I found before merging back into master. It would have left
cleaner logs to have redone those using one final commit for each thing
changed.