Doc: NR improve example of \accepts (issue 44420043)

[k-ohara5a5a]

You want to change the text as well as the example.

Giving four staves lets a user see more clearly what happens if he
removes \accepts.


https://codereview.appspot.com/44420043/diff/1/Documentation/notation/changing-defaults.itely
File Documentation/notation/changing-defaults.itely (right):

https://codereview.appspot.com/44420043/diff/1/Documentation/notation/changing-defaults.itely#newcode1347
Documentation/notation/changing-defaults.itely:1347: from the list.  For
example, it would not normally be desirable for
For example, a square-braced staff group is not usually found within a
curved-braced staff with connecting staff bars, and a @code{GrandStaff}
does not accept a @code{StaffGroup} inside it by default.  If this were
required it can be done:

\new GrandStaff \with {\accepts StaffGroup } <<
  \new Staff { c''1 }
  \new StaffGroup <<
    \new Staff { g'1 }
    \new Staff { e'1 } >>
  \new Staff {c'1 } >>

https://codereview.appspot.com/44420043/