## The current behavior

The full value of the `key` is very difficult / impossible to find and use in the interface of the React Devtools.

![Kapture 2020-04-22 at 11 47 47](https://user-images.githubusercontent.com/1935696/79997715-25222680-84ba-11ea-97ba-51f1679a8c91.gif)

Only managed to find it by accident :(

## The expected behavior

The `key` is visible in the props list to the right.

### Detailed Proposal

As mentioned below in https://github.com/facebook/react/issues/18702#issuecomment-617924196

Add a light divider and new section in the props panel to the right.

Potentially also add a question mark that shows an explanation about the fact that things in this section are not really props.

Ref (Original implementation): https://github.com/facebook/react-devtools/pull/328
className={styles.IconButton}
            onClick={highlightElement}
            title="Inspect the matching DOM element">
            <ButtonIcon type="view-dom" />
          </Button>
        )}
        <Button
          className={styles.IconButton}
          onClick={logElement}
          title="Log this component data to the console">
          <ButtonIcon type="log-data" />
        </Button>
        <Button
          className={styles.IconButton}
          disabled={!canViewSource}
          onClick={viewSource}
          title="View source for this element">
          <ButtonIcon type="view-source" />
        </Button>
      </div>
      {inspectedElement === null && (
        <div className={styles.Loading}>Loading...</div>
      )}
      {inspectedElement !== null && (
        <InspectedElementView
          key={
            inspectedElementID 
          }
          copyInspectedElementPath={copyInspectedElementPath}
          element={element}