doc: dfu: add DFU to HTML documentation

Add the device firmware update functions to the generated HTML
documentation.

Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
Acked-by: Lukasz Majewski <lukma@denx.de>
diff --git a/doc/api/dfu.rst b/doc/api/dfu.rst
new file mode 100644
index 0000000..5bd9e29
--- /dev/null
+++ b/doc/api/dfu.rst
@@ -0,0 +1,7 @@
+.. SPDX-License-Identifier: GPL-2.0+
+
+Device firmware update
+======================
+
+.. kernel-doc:: include/dfu.h
+   :internal: