Figured bass doc patch

[John Mandereau]

Hello,
Here's a patch for the figured bass docs. I tried to follow the "Hints
for style". In general, I wonder whether the snippets should be
real-life examples (I mean, music that that sounds well when you play
it) or simply demonstrate Lily features.

Please read the patch carefully, there are certainly English mistakes
and some other details. For example, I suppose

"Bugs

Slash notation for alterations is not supported."

should be removed if "slash notation for alterations" means "slashed
numbers for diminished intervals", as they are now implemented ;-)

I tested my changes; I had to run 'make web-clean' before 'make web' to
see the changes, which took a while. Is it possible to simply rerun
'make web' to avoid rebuilding the docs from scratch?

Regards
-- 
John Mandereau <address@hidden>