NixOS/nixpkgs — pull request #4601 by DamienCassou (2014-10-20 11:35:03+00:00)
Title: Let systemd units define their documentation

Systemd units can define their documentation through the `Documentation`
option. From `man:systemd.unit(5)`:
```
Documentation=
A space-separated list of URIs referencing documentation for this unit
or its configuration. Accepted are only URIs of the types "http://",
"https://", "file:", "info:", "man:". For more information about the
syntax of these URIs, see uri(7). The URIs should be listed in order
of relevance, starting with the most relevant. It is a good idea to
first reference documentation that explains what the unit's purpose
is, followed by how it is configured, followed by any other related
documentation. This option may be specified more than once, in which
case the specified list of URIs is merged. If the empty string is
assigned to this option, the list is reset and all prior assignments
will have no effect.
```