[doc] breakbefore

[Erik Sandberg]

hi,

When doing some typesetting, I looked for breakbefore in the documentation.

I found that it was pretty hard to find, and not well-documented:
- Page-breaking.html should IMHO contain some comment on how to break between 
scores.
- Creating-titles.html mentions the setting, but doesn't say exactly _how_ to 
use it (I needed to search the mail archives to see that the valid values are 
true and false)

I'd suggest that the setting is documented properly in page-breaking.html, and 
that a link to that page is added in creating-titles.html.

thanks,
Erik