Files which are installed as-is (any .service and other unit files, .conf
files, .policy files, etc), are left as is. My assumption is that SPDX
identifiers are not yet that well known, so it's better to retain the
extended header to avoid any doubt.
I also kept any copyright lines. We can probably remove them, but it'd nice to
obtain explicit acks from all involved authors before doing that.
I figure sooneror later we'll have more of these docs, hence let's give
them a clean place to be.
This leaves NEWS and README/README.md as well as the LICENSE texts in
the root directory of the project since that appears to be customary for
Free Software projects.
