Docs: Add `@since` version for `WP_Locale_Switcher::init()`.

Props keesiemeijer.
Fixes #42798.

git-svn-id: https://develop.svn.wordpress.org/trunk@42395 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-includes/class-wp-locale-switcher.php

@@ -53,6 +53,8 @@ class WP_Locale_Switcher {
 	 * Initializes the locale switcher.
 	 *
 	 * Hooks into the {@see 'locale'} filter to change the locale on the fly.
+	 *
+	 * @since 4.7.0
 	 */
 	public function init() {
 		add_filter( 'locale', array( $this, 'filter_locale' ) );