Docs: Fix indentation in add_filter() example.

See #32246.

git-svn-id: https://develop.svn.wordpress.org/trunk@36392 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-includes/plugin.php

@@ -50,7 +50,7 @@ if ( ! isset( $wp_current_filter ) )
  *
  *     function example_callback( $example ) {
  *         // Maybe modify $example in some way.
- *     	   return $example;
+ *         return $example;
  *     }
  *     add_filter( 'example_filter', 'example_callback' );
  *