LICENSES: Add note to CDDL-1.0 license that it should not be used

The only reason we have the CDDL-1.0 license text around is for some
dual-licensed files from virtualbox. New code should not use this license.

Add a note about this and change the example tag to be dual-licensed.
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

LICENSES/other/CDDL-1.0

 Valid-License-Identifier: CDDL-1.0
 SPDX-URL: https://spdx.org/licenses/CDDL-1.0.html
 Usage-Guide:
+  Do NOT use. The CDDL-1.0 is not GPL compatible. It may only be used for
+  dual-licensed files where the other license is GPL compatible.
+  If you end up using this it MUST be used together with a GPL2 compatible
+  license using "OR".
   To use the Common Development and Distribution License 1.0 put the
   following SPDX tag/value pair into a comment according to the placement
   guidelines in the licensing rules documentation:
-    SPDX-License-Identifier: CDDL-1.0
+    SPDX-License-Identifier: ($GPL-COMPATIBLE-ID OR CDDL-1.0)
 
 License-Text: