Correct puppet-strings documentation for unit_file

puppet-strings uses @param rather than @attr. It also documents the
previously undocumented ensure parameter.

manifests/unit_file.pp

@@ -4,45 +4,48 @@
 #
 # @see systemd.unit(5)
 #
-# @attr name [Pattern['^.+\.(service|socket|device|mount|automount|swap|target|path|timer|slice|scope)$']]
+# @param name [Pattern['^.+\.(service|socket|device|mount|automount|swap|target|path|timer|slice|scope)$']]
 #   The target unit file to create
 #
 #   * Must not contain ``/``
 #
-# @attr path
+# @param ensure
+#   The state of the unit file to ensure
+#
+# @param path
 #   The main systemd configuration path
 #
-# @attr content
+# @param content
 #   The full content of the unit file
 #
 #   * Mutually exclusive with ``$source``
 #
-# @attr source
+# @param source
 #   The ``File`` resource compatible ``source``
 #
 #   * Mutually exclusive with ``$content``
 #
-# @attr target
+# @param target
 #   If set, will force the file to be a symlink to the given target
 #
 #   * Mutually exclusive with both ``$source`` and ``$content``
 #
-# @attr owner
+# @param owner
 #   The owner to set on the unit file
 #
-# @attr group
+# @param group
 #   The group to set on the unit file
 #
-# @attr mode
+# @param mode
 #   The mode to set on the unit file
 #
-# @attr show_diff
+# @param show_diff
 #   Whether to show the diff when updating unit file
 #
-# @attr enable
+# @param enable
 #   If set, will manage the unit enablement status.
 #
-# @attr active
+# @param active
 #   If set, will manage the state of the unit.
 #
 define systemd::unit_file(