Update column-formatting.md

Author: VesaJuvonen

docs/declarative-customization/column-formatting.md

@@ -1,7 +1,7 @@
 ---
 title: Use column formatting to customize SharePoint
 description: Customize how fields in SharePoint lists and libraries are displayed by constructing a JSON object that describes the elements that are displayed when a field is included in a list view, and the styles to be applied to those elements.
-ms.date: 04/19/2018
+ms.date: 08/21/2019
 localization_priority: Priority
 ---