[PATCH] docs: driver-api: documentation build warning fix

Commit 5f653f7590ab7db7379f668b2975744585206b0d rename bus.c to core.c, but introduced a new documentation warnings:

Documentation/driver-api/cxl/memory-devices.rst:32: WARNING: Title underline too short.

CXL Core
-------

Core is longer than bus, so just add a "-"

Signed-off-by: Yanteng Si <redacted>
---
 Documentation/driver-api/cxl/memory-devices.rst | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Documentation/driver-api/cxl/memory-devices.rst b/Documentation/driver-api/cxl/memory-devices.rst
index 71495ed77069..73f6b246c583 100644
--- a/Documentation/driver-api/cxl/memory-devices.rst
+++ b/Documentation/driver-api/cxl/memory-devices.rst

@@ -29,7 +29,7 @@ CXL Memory Device
    :internal:
 
 CXL Core
--------
+--------
 .. kernel-doc:: drivers/cxl/core.c
    :doc: cxl core
 

-- 
2.27.0