Index: wp-admin/about.php
===================================================================
--- wp-admin/about.php	(revision 38247)
+++ wp-admin/about.php	(working copy)
@@ -180,7 +180,13 @@
 			<div class="under-the-hood two-col">
 				<div class="col">
 					<h3><?php _e( 'Customizer APIs for Setting Validation and Notifications' ); ?></h3>
-					<p><?php _e( 'Settings now have an <a href="https://make.wordpress.org/core/2016/07/05/customizer-apis-in-4-6-for-setting-validation-and-notifications/">API for enforcing validation constraints</a>. Likewise Customizer controls now support notifications which are used to display validation errors instead of failing silently.' ); ?></p>
+					<p><?php
+						printf(
+							/* translators: %s: https://make.wordpress.org/core/2016/07/05/customizer-apis-in-4-6-for-setting-validation-and-notifications/  */
+							__( 'Settings now have an <a href="%s">API for enforcing validation constraints</a>. Likewise Customizer controls now support notifications which are used to display validation errors instead of failing silently.' ),
+							'https://make.wordpress.org/core/2016/07/05/customizer-apis-in-4-6-for-setting-validation-and-notifications/'
+						);
+					?></p>
 				</div>
 				<div class="col">
 					<h3><?php _e( 'Multisite, now faster than ever' ); ?></h3>