Add an example for updating copyright and license header

As per discussion in pull-request #931.

CONTRIBUTING.md

@@ -7,6 +7,22 @@ The [OpenHW Work Flow](https://github.com/openhwgroup/core-v-docs/blob/master/ve
 is required reading.  You will find information about the implementation and usage of the CORE-V verification environments
 in the [Verification Strategy](https://github.com/openhwgroup/core-v-docs/blob/master/verif/Common/OpenHWGroup_CORE-V_Verif_Strategy.pdf).
 
+## Updating Copyright
+The files in this repository are open-source artifacts licensed under the terms of the Solderpad license, see [LICENSE](LICENSE).
+If you modify a file, a new copyright _may_ be added, but the existing copyright and license header _must not_ be removed or modified.
+If your contribution uses a newer version of the existing license, you are encouraged to declare that with a one-liner SPDX header.
+
+In the example below, a new copyright and updated license are added to an existing copyright and license:
+```
+// Copyright 2024 OpenHW Group and <member-company>
+// SPDX-License-Identifier: Apache-2.0 WITH SHL-2.1
+// Copyright 2018 ETH Zurich and University of Bologna.
+// Copyright and related rights are licensed under the Solderpad Hardware
+// License, Version 0.51 (the "License"); you may not use this file except in
+// compliance with the License.
+// ...remainder of original license header from ETHZ and UniBo.
+```
+
 ## The Mechanics
 1. From GitHub: [fork](https://help.github.com/articles/fork-a-repo/) the [cv32e40p](https://github.com/openhwgroup/cv32e40p) repository
 2. Clone repository: `git clone https://github.com/[your_github_username]/cv32e40p`