More unhelpful update descriptions

[Bruno Wolff III]

On Fri, Jun 28, 2013 at 17:52:16 -0700,
   Adam Williamson <awilliam at redhat.com> wrote:
>
>I've suggested before that Bodhi should reject any update with an 
>empty description or with the placeholder text as the description. 
>That would be really helpful.

I think it does now. I forgot to add a note when rushing one of the 
spin-kickstarts updates and bodhi didn't work and reminded me to add 
the note.