Date/Time - Custom field formats and widget displays

[alex-cit]

Custom field formats and widget displays were described in the docs as a part of the Date and Time section of Setting Up Widgets in Attributes Form

docs/src/layer/settingup_forms.md

Line 141 in ed82fdd

It is also possible to use custom Field Formats and Widget Displays.

This content was removed in #495 as it is a bit too specific/advanced for this page and should be rewritten for clarity as well. If needed, we can get back to this in the future.