x86: coreboot: Allow building an expo for editing CMOS config

Coreboot provides the CMOS layout in the tables it passes to U-Boot.
Use that to build an editor for the CMOS settings.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/doc/usage/cmd/cbcmos.rst b/doc/usage/cmd/cbcmos.rst
index 156521d..9395cf1 100644
--- a/doc/usage/cmd/cbcmos.rst
+++ b/doc/usage/cmd/cbcmos.rst
@@ -40,3 +40,6 @@
     Checksum 6600 written
     => cbc check
     =>
+
+See also :ref:`cedit_cb_load` which shows an example that includes the
+configuration editor.