docs: add OpenSSF Best Practices registration badge

Author: hyperpolymath

README.adoc

@@ -1,7 +1,10 @@
-image:https://img.shields.io/badge/License-PMPL--1.0-blue.svg[License: PMPL-1.0,link="https://github.com/hyperpolymath/palimpsest-license"]
 // SPDX-License-Identifier: MPL-2.0
+// Copyright (c) Jonathan D.A. Jewell <j.d.a.jewell@open.ac.uk>
+image:https://img.shields.io/badge/License-MPL_2.0--1.0-blue.svg[License: MPL-2.0,link="https://github.com/hyperpolymath/palimpsest-license"]
 // SPDX-FileCopyrightText: 2024 Hyperpolymath
 = Explicit Trust Plane
+image:https://img.shields.io/badge/OpenSSF-Best_Practices-green?logo=openssourcesecurity[OpenSSF Best Practices,link="https://www.bestpractices.dev/en/projects/new?repo_url=https://github.com/hyperpolymath/explicit-trust-plane"]
+
 
 
 
@@ -207,7 +210,7 @@ gpg --version    # gnupg 2.2.0 or later
 
 == License
 
-SPDX-License-Identifier: MPL-2.0-or-later
+SPDX-License-Identifier: MPL-2.0
 
 This project is licensed under the GNU Affero General Public License v3.0 or later.