Twenty Twenty-One: Document the twenty_twenty_one_content_width filter.

Includes removing an unnecessary PHPCS ignore annotation. The linked WPCS issue is not open anymore, and [WordPress/WordPress-Coding-Standards#1773 WordPress/WordPress-Coding-Standards#1773] indicates that the test now makes an exception for `$content_width`.

Follow-up to [49216].

Props viralsampat, pmbaldha, sabernhardt.
Fixes #63664.

git-svn-id: https://develop.svn.wordpress.org/trunk@61070 602fd350-edb4-49c9-b593-d223f7449a82

Author: SergeyBiryukov

src/wp-content/themes/twentytwentyone/functions.php

@@ -375,9 +375,13 @@ function twenty_twenty_one_widgets_init() {
  * @return void
  */
 function twenty_twenty_one_content_width() {
-	// This variable is intended to be overruled from themes.
-	// Open WPCS issue: {@link https://github.com/WordPress-Coding-Standards/WordPress-Coding-Standards/issues/1043}.
-	// phpcs:ignore WordPress.NamingConventions.PrefixAllGlobals.NonPrefixedVariableFound
+	/**
+	 * Filters Twenty Twenty-One content width of the theme.
+	 *
+	 * @since Twenty Twenty-One 1.0
+	 *
+	 * @param int $content_width Content width in pixels.
+	 */
 	$GLOBALS['content_width'] = apply_filters( 'twenty_twenty_one_content_width', 750 );
 }
 add_action( 'after_setup_theme', 'twenty_twenty_one_content_width', 0 );