docs: Update known issues with vHost RFC2544 packet loss issue

Change-Id: I7adfa8c9d90c04c79568df2ce1f856d39217405f
Signed-off-by: Meghan Halton <meghan.halton@intel.com>
Reviewed-by: Mark B. Kavanagh <mark.b.kavanagh@intel.com>
Reviewed-by: Rory Sexton <rory.sexton@intel.com>