[PHP-NOTES] Deleted 1 old and low rated notes

Following were the 1 notes with a rating less than -5 and
are older than 1 year.

These notes represented 0.0% of the 15435 total user notes,
and have now been removed.

Rating | Note
-------+---------------------------------------------------------
   -6  | https://php.net/manual/en/security.hiding.php#43240