docs: add comment

Author: kenjis

system/Database/BaseBuilder.php

@@ -761,9 +761,9 @@ protected function whereHaving(string $qbKey, $key, $value = null, string $type
                     $k = trim($k);
 
                     end($op);
-
                     $op = trim(current($op));
 
+                    // Does the key end with operator?
                     if (substr($k, -strlen($op)) === $op) {
                         $k  = rtrim(substr($k, 0, -strlen($op)));
                         $op = " {$op}";