Signature Syntax and Processing Overview section

Attached is the best I can come up with so far.  I don't think we are
really clear on just what is going on with Object, Manifest/Package, and
attributes elements.  Probably either Manifest/Package and attributes
elements are always included in an Object  and are an Object type or
else they should be able to appear in Signature at the same level as Object.

I'll also post a separate message on SignedInfo canonicalization.

Thanks,
Donald