message: doc: Qualify GNU licenses in example license field
  Since SPDX License list 3.0, unqualified GNU licenses are deprecated:
  We use version 3.6 of the list so we should not use the deprecated licenses.
diff: @@ -218,8 +218,8 @@ the user must comply with both licenses simultaneously. The `WITH` operator
  indicates a license with a special exception. Some examples:
  * `MIT OR Apache-2.0`
  -* `LGPL-2.1 AND MIT AND BSD-2-Clause`
  -* `GPL-2.0+ WITH Bison-exception-2.2`
  +* `LGPL-2.1-only AND MIT AND BSD-2-Clause`
  +* `GPL-2.0-or-later WITH Bison-exception-2.2`
  If a package is using a nonstandard license, then the `license-file` field may
  be specified in lieu of the `license` field.
  