refactor: declare that our website works both in light and dark mode

Author: mfranzke

source/_meta/_head.hbs

@@ -13,6 +13,9 @@
 	{{! <link rel="manifest" href="../../site.webmanifest"> }}
 	{{! <link rel="apple-touch-icon" href="../../images/db_logo.svg"> }}
 
+	<!-- Declare that our website works both in light and dark mode //-->
+	<meta name="color-scheme" content="dark light">
+
 	<!-- If you're adapting the HTML out of this document, only include the following CSS file, as the other below are related to pattern lab styling and presenting our patterns in this context even only //-->
 	<link rel="stylesheet" href="../../css/{{ domain }}/db-ui-core.css?{{ cacheBuster }}" media="all">