Systemd services are permitted to be scripts, as well as binary
executables.
The same also applies to the underlying /sbin/mount and /sbin/swapon.
It is not necessary for the user to consider what type of program file
these are. Nor is it necessary with systemd-nspawn, to distinguish between
init as a "binary" v.s. a user-specified "program".
Also fix a couple of grammar nits in the modified sentences.
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.
It has fairly wide functionality now and the interface has been
stable for a while. It it a useful testing tool.
The name is changed to better indicate what it does.
