user view of website+docs

[Graham Percival]

How does this look?
http://kainhofer.com/~lilypond/Documentation/general/Manuals.html
http://kainhofer.com/~lilypond/Documentation/general/Learning.html

The second-layer TOC is obviously a work in progress.


Only Learning, Essay, and All have been done so far (and All is
only half-done).  If we like the look of this, doing the rest in
the same style will be easy.

I'm not certain if we want to include info in the list of doc
formats.  I can't imagine people wanting to download the info
files (as opposed to having them installed along with a package or
from compiling the source), but OTOH, there's no harm dumping the
link there.

Cheers,
- Graham