docs/devel/lockcnt: Include kernel-doc API documentation

Pull in the kernel-doc API documentation into the lockcnt docs.
This requires us to fix one rST markup syntax error in the
header file comments.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Message-id: 20240816132212.3602106-8-peter.maydell@linaro.org

docs/devel/lockcnt.rst

@@ -175,7 +175,7 @@ three instructions in the critical path, two assignments and a ``smp_wmb()``.
 ``QemuLockCnt`` API
 -------------------
 
-The ``QemuLockCnt`` API is described in ``include/qemu/lockcnt.h``.
+.. kernel-doc:: include/qemu/lockcnt.h
 
 
 ``QemuLockCnt`` usage

include/qemu/lockcnt.h

@@ -51,7 +51,7 @@ void qemu_lockcnt_destroy(QemuLockCnt *lockcnt);
  * Because this function can wait on the mutex, it must not be
  * called while the lockcnt's mutex is held by the current thread.
  * For the same reason, qemu_lockcnt_inc can also contribute to
- * AB-BA deadlocks.  This is a sample deadlock scenario:
+ * AB-BA deadlocks.  This is a sample deadlock scenario::
  *
  *            thread 1                      thread 2
  *            -------------------------------------------------------