Improve Custom Node documentation

Author: CarlosNZ

README.md

@@ -670,7 +670,9 @@ Custom nodes are provided in the `customNodeDefinitions` prop, as an array of ob
 
 The `condition` is just a [Filter function](#filter-functions), with the same input parameters (`key`, `path`, `value`, etc.), and `element` is a React component. Every node in the data structure will be run through each condition function, and any that match will be replaced by your custom component. Note that if a node matches more than one custom definition conditions (from multiple components), the *first* one will be used, so place them in the array in priority order.
 
-The component will receive *all* the same props as a standard node component (see codebase), but you can pass additional props to your component if required through the `customNodeProps` object. A thorough example of a custom Date picker is used in the demo (along with a couple of other more basic presentational ones), which you can inspect to see how to utilise the standard props and a couple of custom props. View the source code [here](https://github.com/CarlosNZ/json-edit-react/blob/main/demo/src/customComponents/DateTimePicker.tsx)
+The component will receive *all* the same props as a standard node component plus some additional ones — see [BaseNodeProps](https://github.com/CarlosNZ/json-edit-react/blob/b085f6391dabf574809f1040b11401c13344923d/src/types.ts#L219-L265) (common to all nodes) and [CustomNodeProps](https://github.com/CarlosNZ/json-edit-react/blob/b085f6391dabf574809f1040b11401c13344923d/src/types.ts#L275-L287) type definitions. Specifically, if you want to update the data structure from your custom node, you'll need to call the `setValue` method on your node's data value.
+
+You can pass additional props specific to your component, if required, through the `customNodeProps` object. A thorough example of a custom **Date Picker** is used in the demo (along with a couple of other more basic presentational ones), which you can inspect to see how to utilise the standard props and a couple of custom props. View the source code [here](https://github.com/CarlosNZ/json-edit-react/blob/main/demo/src/customComponents/DateTimePicker.tsx).
 
 By default, your component will be presented to the right of the property key it belongs to, like any other value. However, you can hide the key itself by setting `hideKey: true`, and the custom component will take the whole row. (See the "Presented by" box in the "Custom Nodes" data set for an example.)