[PATCH] Documentation/driver-api: nvdimm: Fix sphinx build error

[Wan Jiabing]

Fix the following 'make htmldocs' error:

Sphinx parallel build error:
docutils.utils.SystemMessage: ./Documentation/driver-api/nvdimm/nvdimm.rst:
146: (SEVERE/4) Title level inconsistent:

PMEM-REGIONs, Atomic Sectors, and DAX
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Fixes: f8669f1d6a86 ("nvdimm/blk: Delete the block-aperture window driver")
Signed-off-by: Wan Jiabing <wanjiabing@xxxxxxxx>
---
 Documentation/driver-api/nvdimm/nvdimm.rst | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Documentation/driver-api/nvdimm/nvdimm.rst b/Documentation/driver-api/nvdimm/nvdimm.rst
index 7917f6471092..8e6922583571 100644
--- a/Documentation/driver-api/nvdimm/nvdimm.rst
+++ b/Documentation/driver-api/nvdimm/nvdimm.rst
@@ -144,7 +144,7 @@ can be immediately attached to nd_pmem. This latter mode is called
 label-less or "legacy".
 
 PMEM-REGIONs, Atomic Sectors, and DAX
-^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+-------------------------------------
 
 For the cases where an application or filesystem still needs atomic sector
 update guarantees it can register a BTT on a PMEM device or partition.  See
-- 
2.35.1