AU: Updated CLI preview option for lilypond (issue 5716056)

[dak]

http://codereview.appspot.com/5716056/diff/2001/Documentation/usage/running.itely
File Documentation/usage/running.itely (right):

http://codereview.appspot.com/5716056/diff/2001/Documentation/usage/running.itely#newcode282
Documentation/usage/running.itely:282: variable
@option{print-all-headers = ##t}.
Oops, this one is not an option.  It is actually nothing sensible at
all: it is an assignment in LilyPond syntax called a @code{\paper}
variable.

Maybe "if the @code{\paper} variable @code{print-all-headers} is set to
@code{#t}".

http://codereview.appspot.com/5716056/