Deleted 3 old and low rated notes

Following were the 3 notes with a rating less than -5 and
are older than 1 year.

These notes represented 0.0% of the 15870 total user notes,
and have now been removed.

Rating | Note
-------+---------------------------------------------------------
   -6  | https://php.net/manual/en/function.dl.php#36679
   -6  | https://php.net/manual/en/function.imagecreate.php#77195
   -6  | https://php.net/manual/en/function.highlight-string.php#83136