Docs: Replace @returns tags in JS docs with @return.

Per the documentation standards, `@returns` is an unsupported synonym, `@return` should be used instead:
https://make.wordpress.org/core/handbook/best-practices/inline-documentation-standards/javascript/

See #48303.
Built from https://develop.svn.wordpress.org/trunk@46800


git-svn-id: http://core.svn.wordpress.org/trunk@46600 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-admin/js/custom-header.js

@@ -33,7 +33,7 @@
 		 * @since 3.5.0
 		 * @deprecated 4.1.0
 		 *
-		 * @returns {void}
+		 * @return {void}
 		 */
 		$('#choose-from-library-link').click( function( event ) {
 			var $el = $(this);
@@ -71,7 +71,7 @@
 			 * @since 3.5.0
 			 * @deprecated 4.1.0
 			 *
-			 * @returns {void}
+			 * @return {void}
 			 */
 			frame.on( 'select', function() {
 				// Grab the selected attachment.