VSIPL16 — Unclear antecedent in ~Dense() destructor description

The description of the ~Dense() destructor states "It should no longer
be used." The antecedent of "it" is grammatically unclear – although
users can guess from context, this should really say "The Dense object
should no longer be used."

It may perhaps be worth noting explicitly that any views bound to the
block should also not be used (although, in that case, what exactly does
"used" mean? Is it valid to access their size?).