Re: ISSUE-77: Reference threat work in wsc-usecases

> A first stab is here:
> 
>   http://www.w3.org/2006/WSC/drafts/threats/Overview.html
> 
> Language for the use case note:
> 
>    Threats which are in scope for the work described in this
>    Note are further discussed below.  A comprehensive threat
>    tree is work in progress. [WSC-threats]
> 

Since you're willing to keep WSC-threats in line with progress on the 
topic with the WG, I'm good with this alternate proposal.