DataTypeDatalist: explain target type...

...for those in doubt about what choosing "Array" might mean

fixes #1264

doc/82-Changelog.md

@@ -29,7 +29,7 @@ next (will be 1.8.0)
 * FEATURE: Notification Apply Rules as a DirectorObject DataField (#2199)
 * FEATURE: Hint and Error styling has been unified and improved
 * FEATURE: Form field rendering for sets now deals with invalid values
-* FEATURE: Better description for time-based form fields (#1897)
+* FEATURE: Better descriptions for time-based and other fields (#1897, #1264)
 
 ### Translations
 * FEATURE: Italian is now available (#2080)

library/Director/DataType/DataTypeDatalist.php

@@ -130,6 +130,11 @@ class DataTypeDatalist extends DataTypeHook
                 'string' => $form->translate('String'),
                 'array'  => $form->translate('Array'),
             ]),
+            'description' => $form->translate(
+                'Whether this should be a String or an Array in the generated'
+                . ' Icinga configuration. In case you opt for Array, Director'
+                . ' users will be able to select multiple elements from the list'
+            ),
             'required' => true,
         ]);