Remove unused descriptionFrom property

Removes unused descriptionFrom property that was probably copy-pasta remnants from the RecordFinder formwidget when nameFrom was implemented in 6aaf4cce43. Also removed it from the docs here: 6164e4a9e7

modules/backend/formwidgets/Relation.php

@@ -28,11 +28,6 @@ class Relation extends FormWidgetBase
      */
     public $nameFrom = 'name';
 
-    /**
-     * @var string Model column to use for the description reference
-     */
-    public $descriptionFrom = 'description';
-
     /**
      * @var string Custom SQL column selection to use for the name reference
      */
@@ -69,7 +64,6 @@ class Relation extends FormWidgetBase
     {
         $this->fillFromConfig([
             'nameFrom',
-            'descriptionFrom',
             'emptyOption',
             'scope',
         ]);