DescriptionTag

This one is pretty simple.

/**
 * @todo Add some code to this function
 * @note That code should be good
 */
function foo()
{

}

@todo tag is predefined in PhpDocumentor::tags() as an instance of DescriptionTag, so we only need to define @note tag instance.

$doc = (new ReflectionFunction('foo'))->getDocComment();
$customTags = [new DescriptionTag('note')];

$notations = getNotations($doc, $customTags);
var_export($notations);

That results in

[
    'todo' => 'Add some code to this function',
    'note' => 'That code should be good'
]