doc: add include/dm/uclass.h to the HTML documentation

Correct Sphinx style comments in include/dm/uclass.h
and add the driver model UCLASS API to the HTML documentation.

Signed-off-by: Patrick Delaunay <patrick.delaunay@foss.st.com>
Reviewed-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
diff --git a/doc/api/dm.rst b/doc/api/dm.rst
new file mode 100644
index 0000000..edce25d
--- /dev/null
+++ b/doc/api/dm.rst
@@ -0,0 +1,9 @@
+.. SPDX-License-Identifier: GPL-2.0+
+
+Driver Model
+============
+
+Uclass and Driver
+-----------------
+
+.. kernel-doc:: include/dm/uclass.h