For the markdown version of the license book, the generator currently creates null links for CDDL 1.1 and EDL 1.0 entries. This makes the link checker of the docs fail.

AT:

• These entries link to https://spdx.org/licenses/CDDL-1.1.html or https://www.eclipse.org/org/documents/edl-v10.php respectively
• In case we haven't got a license link yet, the generator should not generate a link element (to make sure we only generate valid links always satisfy the link checker)