Deleted 4 old and low rated notes

Following were the 4 notes with a rating less than -5 and
are older than 1 year.

These notes represented 0.0% of the 17354 total user notes,
and have now been removed.

Rating | Note
-------+---------------------------------------------------------
   -6  | https://php.net/manual/en/security.apache.php#85091
   -6  | https://php.net/manual/en/pdo.setattribute.php#123314
   -6  | https://php.net/manual/en/migration80.incompatible.php#127931
   -6  | https://php.net/manual/en/function.array-merge.php#126928