[PATCH v3] doc: clean vhost async path doc

[xuan.ding at intel.com]

From: Xuan Ding <xuan.ding at intel.com>

This patch moves the 'Recommended IOVA mode in async datapath'
section under 'Vhost asynchronous data path' as a sub-section,
which makes the doc cleaner.

Signed-off-by: Xuan Ding <xuan.ding at intel.com>
Reviewed-by: Jiayu Hu <jiayu.hu at intel.com>
---
v3:
* add Reviewd-by

v2:
* fix a typo in commit log
---
 doc/guides/prog_guide/vhost_lib.rst | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/doc/guides/prog_guide/vhost_lib.rst b/doc/guides/prog_guide/vhost_lib.rst
index 628db3fc38..e93673ce68 100644
--- a/doc/guides/prog_guide/vhost_lib.rst
+++ b/doc/guides/prog_guide/vhost_lib.rst
@@ -488,11 +488,11 @@ support sharing DMA channels among vrings.
   not poll completed will cause the DMA ring to be full, which will
   result in packet loss eventually.
 
-Recommended IOVA mode in async datapath
----------------------------------------
+* Recommended IOVA mode in async datapath
 
-When DMA devices are bound to VFIO driver, VA mode is recommended.
-For PA mode, page by page mapping may exceed IOMMU's max capability,
-better to use 1G guest hugepage.
+  When DMA devices are bound to VFIO driver, VA mode is recommended.
+  For PA mode, page by page mapping may exceed IOMMU's max capability,
+  better to use 1G guest hugepage.
 
-For UIO driver, any VFIO related error message can be ignored.
+  For UIO driver or kernel driver, any VFIO related error messages
+  can be ignored.
-- 
2.17.1