Update docs

Author: wojtekmaj

README.md

@@ -119,6 +119,7 @@ Displays an input field complete with custom inputs, native input, a calendar, a
 | onChange             | Function called when the user picks a valid datetime. If any of the fields were excluded using custom `format`, `new Date(y, 0, 1, 0, 0, 0)`, where `y` is the current year, is going to serve as a "base".                                                                                                                        | n/a                     | `(value) => alert('New date is: ', value)`                                                                     |
 | onClockClose         | Function called when the clock closes.                                                                                                                                                                                                                                                                                             | n/a                     | `() => alert('Clock closed')`                                                                                  |
 | onClockOpen          | Function called when the clock opens.                                                                                                                                                                                                                                                                                              | n/a                     | `() => alert('Clock opened')`                                                                                  |
+| onFocus              | Function called when the focuses an input.                                                                                                                                                                                                                                                                                         | n/a                     | `(event) => alert('Focused input: ', event.target.name)`                                                       |
 | openWidgetsOnFocus   | Whether to open the widgets on input focus.                                                                                                                                                                                                                                                                                        | `true`                  | `false`                                                                                                        |
 | portalContainer      | Element to render the widgets in using portal.                                                                                                                                                                                                                                                                                     | n/a                     | `document.getElementById('my-div')`                                                                            |
 | returnValue          | Which dates shall be passed by the calendar to the onChange function and onClick{Period} functions. Can be `"start"`, `"end"` or `"range"`. The latter will cause an array with start and end values to be passed.                                                                                                                 | ` "start"`              | `"range"`                                                                                                      |