Incorrect Calendar Field format example.

[Chris-OW]

On this page https://manual.joomla.org/docs/general-concepts/forms-fields/standard-fields/calendar/
Under format, with showtime, it gives an example of "%Y-%m-%d %H:%i:%s".

This will not format correctly. The %i and %s won't work.

It should be "%Y-%m-%d %H:%M:%S"

[Akshay10258]

The fix is simple and has passed all tests. Please review and merge when you have a moment.