doc: fix format in virtio guide
doc: fix format in virtio guide

This patch removes an unwanted empty line in a sentence.

Fixes: 71afcefbd53e ("doc: update virtio ring size and header size")
Cc: stable@dpdk.org

Signed-off-by: Tiwei Bie <f338cf29d7d69ff1bc99f755ebfb0eb0accd409e@intel.com>
Reviewed-by: Maxime Coquelin <9a2667dee3b90866bbc9c2696cff2b7d5616c95a@redhat.com>

john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk