Specify font license according to REUSE spec

LICENSES/LicenseRef-SJFonts.txt

@@ -5,7 +5,8 @@ Copyright Holder: Steve JORDI steve @ sjordi.com
 License:
 
 SJFonts are licensed under the GNU General Public License version 2 or
-later (see COPYING file) but with the following exception:
+later (see LICENSES/GPL-2.0-or-later.txt file) but with the following
+exception:
 
 As a special exception, if you create a document which uses this font,
 and embed this font or unaltered portions of this font into the document,

fonts/steve.ttf.license

+SPDX-FileCopyrightText: Steve JORDI <steve @ sjordi.com>
+SPDX-License-Identifier: GPL-2.0-or-later OR LicenseRef-SJFonts