Draft: simple update description guidelines

[Orcan Ogetbil]

This would be my suggestion. It is not only less strict but also
informative. I didn't know what the description field in the Bodhi
interface does until 2 months after I started packaging stuff, because
I don't use PackageKit very often. I don't think the wiki explains
what that field is for. Correct me if I'm wrong.

s@
> * All Updates must refer to a upstream changelog or equivalent if one
> exists. Otherwise a brief description (a couple of sentence at most)
> justifying the need for an update must be provided by the maintainers
> pushing the update.
@
* The description field in the bodhi interface is what the users will see on
the PackageKit GUI regarding the significance of the update. This is not
the same thing as the SPEC file changelog. It would be nice to include the
release highlights in this field together with a URL to the upstream changelog,
if there is any.
@

Cheers,
Orcan