[1.3.X] Added note about deprecation of project-level translations to the...

[1.3.X] Added note about deprecation of project-level translations to the deprecation timeline document.

Thanks Jannis for the report. Fixes #17588.

Backport of [17394] from trunk.

git-svn-id: http://code.djangoproject.com/svn/django/branches/releases/1.3.X@17395 bcc190cf-cafb-0310-a4f2-bffc1f526a37