Updated docblock

src/PostgresDriver/Cursor.php

@@ -10,7 +10,9 @@ use Dibi\Connection;
 /**
  * PostgreSQL cursor driver
  *
- * Basic envelope over postgres' cursor, without proper check for edge cases.
+ * Basic envelope over PostgreSQL's cursor. This cursor envelope does not know
+ * cursor position, thus cannot do boundary checks. If you reach end, you simply
+ * get no more values.
  *
  * @package Grifart\Mappi\Store\PostgresDriver
  */
@@ -41,7 +43,6 @@ class Cursor implements ICursor
 		return $this->name;
 	}
 
-
 	public function moveTo(int $index)
 	{
 		$result = $this->getConnection()->query(