docs: kvm: review-checklist.txt: rename to ReST

This file is already in ReST compatible format.
So, rename it and add to the kvm's index.rst.

While here, use the standard conversion for document titles.

Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>