changes.tely: declare MacOSX unsupported (issue 5694092)

[janek . lilypond]

Maybe add some encouragement for getting involved?


http://codereview.appspot.com/5694092/diff/1/Documentation/changes.tely
File Documentation/changes.tely (right):

http://codereview.appspot.com/5694092/diff/1/Documentation/changes.tely#newcode71
Documentation/changes.tely:71: provide timely and reliable releases on
supported platforms.
I would add "If you are interested in making MacOSX a supported platform
again, feel free to contact us if you are willing do to regular MacOS
maintenance (you can also hire someone to do this)."

http://codereview.appspot.com/5694092/