Doc: Added new option 'papersize' to Usage (issue4289057)

[percival . music . ca]

http://codereview.appspot.com/4289057/diff/1/Documentation/usage/lilypond-book.itely
File Documentation/usage/lilypond-book.itely (right):

http://codereview.appspot.com/4289057/diff/1/Documentation/usage/lilypond-book.itely#newcode607
Documentation/usage/lilypond-book.itely:607: @code{'landscape} can also
be used.
oh neat -- if you want a8 landscape, do you put two papersize?  or is it
a8landscape ?  or "a8 landscape" ?

http://codereview.appspot.com/4289057/diff/1/Documentation/usage/lilypond-book.itely#newcode613
Documentation/usage/lilypond-book.itely:613: If a @code{tagline} is
required, either default or custom, then the
The tagline thing has nothing to do with the papersize; please place it
in a more appropriate location in the docs".

http://codereview.appspot.com/4289057/