Misleading documentation on accepted formats by Date Validator

[lgomezma]

In the documentation it is mention that the format option accepts any format allowed by the PHP date() function. This seems not to be the case since it seems to be using the method DateTime::createFromFormat in order to validate the date, and this only accepts a subset of the formats that date() does.

For example a perfectly valid format such as N to get the day of the week as an integer from 1 to 7 would not be valid for the Date Validator.