Merge pull request #16405 from philandstuff/better-dbus-services-packages-docstring

services.dbus module: more complete docstring

nixos/modules/services/system/dbus.nix

···
         default = [ ];
         description = ''
           Packages whose D-Bus configuration files should be included in
-          the configuration of the D-Bus system-wide message bus.
-          Specifically, every file in
+          the configuration of the D-Bus system-wide or session-wide
+          message bus.  Specifically, files in the following directories
+          will be included into their respective DBus configuration paths:
           <filename><replaceable>pkg</replaceable>/etc/dbus-1/system.d</filename>
-          is included.
+          <filename><replaceable>pkg</replaceable>/share/dbus-1/system-services</filename>
+          <filename><replaceable>pkg</replaceable>/etc/dbus-1/session.d</filename>
+          <filename><replaceable>pkg</replaceable>/share/dbus-1/services</filename>
         '';
       };