Proposal: Include css for docs in emacs repo

[Daniel Radetsky <dradetsky@gmail.com>]

I would like to build the emacs manuals for local use. This
means the one-page-per-node manuals. Ideally, I'd like to
build them with one command, and generate a self-contained
directory I could chuck somewhere (e.g. under my designated
serve-docs-from-local dir) and be able to browse them just
like I can on the gnu site.

Even if the docs build itself didn't currently leave
something to be desired, the built docs will contain the
following

<style type="text/css">
@import url('/software/emacs/manual.css');
</style>

Which refers to css not included in the repo itself. I'm not
sure if it's included in any repo. Personally, I just
downloaded the file (and the style.css file it referenced)
off of gnu.org. It would be nice if instead, these 2 files
were placed in a manual-assets/ dir alongside emacs/ elisp/
and friends, and if the manuals were to reference the
manual.css file contained in this dir with a relative path,
rather than the one at /software/emacs/manual.css.

There's no reason why gnu.org couldn't override this file
somehow, such that e.g. all manuals served from gnu.org
would continue to use /software/emacs/style.css instead of
the relative one, although I can't see why you'd want to.
But you could.

Anyway, I could concievably hack on the manual-generating
scripts myself (especially if the release-process docs were
a little clearer), but it won't actually accomplish my
purpose if we haven't moved the css to the emacs repo.