Remove arabic.ly from common note name languages. (issue2755041)

[v . villenave]

Reviewers: ,

Message:
Greetings everybody,

This commit could make it easier for me to document upcoming changes to
the note names selection syntax.

Please have a look, and feel free to push if it's okay.



Description:
Remove arabic.ly from common note name languages.

Please review this at http://codereview.appspot.com/2755041/

Affected files:
  M Documentation/notation/pitches.itely
  M Documentation/notation/world.itely