Feature: #89507 - Add description for TCA palettes

See forge#89507


A new TCA property description on palettes entry level has been introduced. If provided, the FormEngine will render its value below the palette label, similar to the TCA field description. The value data type is the same as for the palette label: a localized string. This additional help text can therefore be used to clarify some field usages directly in the UI.

Example usage:

'types' => [
    '0' => [
        'showitem' => '

'palettes' => [
    'palette_1' => [
        'label' => 'palette_1',
        'description' => 'palette_1_description',
        'showitem' => 'palette_field_1, palette_field_2, palette_field_3',


Integrators now have the ability to add additional information to TCA palettes, supporting editors on their daily work.