Docs: Correct type for the $data parameter of WP_Theme::cache_add().

Props itowhid06.
Fixes #48096.

git-svn-id: https://develop.svn.wordpress.org/trunk@46226 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-includes/class-wp-theme.php

@@ -678,7 +678,7 @@ final class WP_Theme implements ArrayAccess {
 	 * @since 3.4.0
 	 *
 	 * @param string $key Type of data to store (theme, screenshot, headers, post_templates)
-	 * @param string $data Data to store
+	 * @param array|string $data Data to store
 	 * @return bool Return value from wp_cache_add()
 	 */
 	private function cache_add( $key, $data ) {