[Docs] Fix scoped noalias example

Summary:
As far as I understand the entire point of this example is to show that
if noalias is not a superset/equal to the alias.scope list on a scope
domain then load could reference locations that the store is not known
to not-alias i.e may alias.

Reviewers: hfinkel

Reviewed By: hfinkel

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D9598

llvm-svn: 236977