Ambitus snippet

[Phil Holmes]

I think the snippet at:

http://lilypond.org/doc/v2.19/Documentation/snippets/contexts-and-engravers#contexts-and-engravers-defining-an-engraver-in-scheme_003a-ambitus-engraver

is rather complex to be included in the docs: I don't see why one would want
to rewrite existing capability?

Anyone object to its removal from the docs? (I'd create it on the LSR
assuming it works there).