I18N: Capitalize translator comments consistently, add trailing punctuation.

Includes minor code layout fixes.

See #44360.

git-svn-id: https://develop.svn.wordpress.org/trunk@45932 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-admin/customize.php

@@ -207,7 +207,7 @@ do_action( 'customize_controls_print_scripts' );
 					<div class="accordion-section-title">
 						<span class="preview-notice">
 						<?php
-							/* translators: %s: Site title */
+							/* translators: %s: The site/panel title in the Customizer. */
 							echo sprintf( __( 'You are customizing %s' ), '<strong class="panel-title site-title">' . get_bloginfo( 'name', 'display' ) . '</strong>' );
 						?>
 						</span>