The licence should be referenced directly in the README
This results from a discussion with David Margery following this request:
Dear contact,
You are identified in the BIL (Software Information Base) as the reference contact for the software MoReFEM (https://bil.inria.fr/en/software/view/3253/tab).
Following the update of the open source licence list to version 2.3 of the SPDX repository, the licence declared for the software MoReFEM, i.e. LGPL-3.0, is an obsolete identifier because it is ambiguous. Please connect to the BIL, and update the data by specifying between LGPL-3.0-only and "LGPL-3.0-or-later" according to the Licence file in your git repository.
Thank you for your collaboration
All the best,
David
I thought the LICENCE.md file was self sufficient; it is better to add a paragraph in the README that specifies which licence and the modality for its evolution.