Make documentation reflect presence of \tuplet (issue 7220052)

[k-ohara5a5a]

Looks great.

You can simplify the version in changes.  The two tuplets sharing share
one beam catches the eye, but that was not the change.  I wrote a
version below imagining a reader who has forgotten that the fraction in
\times is backwards, and didn't yet notice that LilyPond commands can
have optional arguments. Use what you like.


https://codereview.appspot.com/7220052/diff/1/Documentation/changes.tely
File Documentation/changes.tely (right):

https://codereview.appspot.com/7220052/diff/1/Documentation/changes.tely#newcode76
Documentation/changes.tely:76:
Tuplets are now created with the @code{\tuplet} command, which takes a
fraction @code{t/n} to specify that @var{t} notes are played in the time
usually allowed for @var{n}. One @code{\tuplet} command can create
several tuplets if their duration is typed after the fraction.
@lilypond[quote,verbatim,relative=2]
\tuplet 3/2 { c8 d e } \tuplet 3/2 { f e d } c2
\tuplet 3/2 4 { c8 d e f e d } c2
@end lilypond
The @code{\times} command, taking the reverse order in the fraction,
still functions.

https://codereview.appspot.com/7220052/