Use SPDX descriptors here, and in CamlPDF

[johnwhitington]

And consider REUSE.toml.

The Fedora spec files are a good place to start:

CPDF:
#All AGPL-3.0-only except cpdfxmlm.ml* which are ISC and cpdfyojson.ml* which
#are BSD-3-Clause and the textual Matterhorn protocol error descriptions in
#cpdfua.ml which are CC-BY-4.0 and the files cpdfunicodedata.* which are
#Unicode-DFS-2015
License: AGPL-3.0-only and ISC and BSD-3-Clause and CC-BY-4.0 and Unicode-DFS-2015

CamlPDF:
#Entire source is LGPL-2.1-or-later WITH OCaml-LGPL-linking exception except
#rijndael-alg-fst* which is LicenseRef-Fedora-Public-Domain, sha2.* which is
#BSD-3-Clause, miniz.* which is MIT and Unlicense, and pdfafmdata.* which is
#APAFML
License: LGPL-2.1-or-later WITH OCaml-LGPL-linking-exception and LicenseRef-Fedora-Public-Domain and BSD-3-Clause and MIT and Unlicense and APAFML