Document Y format footgun

[homersimpsons]

Updated descriptions for Y format to clearly shows that 2 digit years may lead to unexpected results.

I removed 0055 as the same example is provided as 0025.

To me this is not clear enough, I wanted to parse a Y-m-d or y-m-d:

$date = '25-10-13';
$parsed = DateTime::createFromFormat('Y-m-d', $date) ?: DateTime::createFromFormat('y-m-d', $date); // 13-10-0025
$parsed = DateTime::createFromFormat('y-m-d', $date) ?: DateTime::createFromFormat('Y-m-d', $date); // 13-10-2025