[DAS2] DAS intro

[Ed Erwin]

Andrew Dalke wrote:
> The front of the DAS doc starts
> 
>   DAS 2.0 is designed to address the shortcomings of DAS 1.0, including:
> 
> That kinda assumes people know what DAS 1.0 is to understand DAS 2.0.
> 
> How about this instead, as an overview/introduction.
> 
>  ======
> 
> DAS/2 describes a data model for genome annotations.  

In general I like this better than the original introduction.  Thanks 
for writing it.

But I agree with Andreas that the first line is better as:

 > DAS/2  is a protocol to share biological data.

I definitely think of DAS as a protocol first, rather than a data model 
first.