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 16032 total user notes,
and have now been removed.

Rating | Note
-------+---------------------------------------------------------
   -9  | https://php.net/manual/en/mbstring.installation.php#128366
   -8  | https://php.net/manual/en/function.mt-rand.php#113611
   -6  | https://php.net/manual/en/function.var-dump.php#70084