Study and adapt Software Package Data Exchange Specification

[devraj]

I found SPDX as part of migrating to hatch when I created a sample project and it had a header like

# SPDX-FileCopyrightText: 2024-present Dev Mukherjee <de...@g....com>
#
# SPDX-License-Identifier: MIT

We should study the relevant directives like SPDX-License-Identifier and then add it to each relevant header or the project on the whole.