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.
As requested in
https://github.com/systemd/systemd/pull/4864#pullrequestreview-12372557.
docbook will substitute triple dots for the ellipsis in man output, so this has
no effect on the troff output, only on HTML, making it infinitesimally nicer.
In some places we show output from programs, which use dots, and those places
should not be changed. In some tables, the alignment would change if dots were
changed to the ellipsis which is only one character. Since docbook replaces the
ellipsis automatically, we should leave those be. This patch changes all other
places.
