packed-ring: fix plurals

There are two instances where plural needs to be used instead of
singular:

1. "descriptor(s)" is used later in the text, so use it consistently
   instead of starting with "descriptor" and switching later.

2. "What follows is the requirements" ->
   "What follows are the requirements"

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Fixes: https://github.com/oasis-tcs/virtio-spec/issues/7
Approved-by: https://www.oasis-open.org/committees/ballot.php?id=3184

0 files changed, 0 insertions, 0 deletions