You can add hints to form elements (including blocks and sections) using the hint props. You can defined the positioning of the hint (top or bottom) using the hintPosition props. It accepts either of these values: TOP or BOTTOM (case sensitive). Default is BOTTOM
{
"type": "input",
"key": "Text",
"props": {
"label": "Text Field",
"hint": "This is a hint",
"hintPosition": "TOP"
},
}