Attribute documentation

[Aaron Ballman]

On Mon, Feb 10, 2014 at 12:36 PM, Jordan Rose <jordan_rose at apple.com> wrote:
> At some point (now?) we should probably set up diagtool (or similar) to warn about new attributes without documentation, the same way we do new warnings without flags.

The way I have it set up currently, you'll get an error if you attempt
to add an attribute without marking its documentation. However,
"undocumented" counts as documentation.

~Aaron