DataHandler documentation improvements

[sypets]

• process_datamap does not exist at all on that page.
• process_cmdmap exists, but is not really explained
• how to get the uid of a new record created with datamap?
• There is a full basic example ("Basic usage") at the top of the page, the other examples in "Examples of data submission" are incomplete (because they only initialize an array and do not pass it to datahandler and have to be combined with the example at the top

https://docs.typo3.org/m/typo3/reference-coreapi/main/en-us/ApiOverview/Typo3CoreEngine/Database/Index.html

Further information is on this page:

Using the DataHandler in scripts

so the information is actually there.

---

In the core, there are several examples, in the testing classes, e.g.

typo3/sysext/core/Tests/Functional/DataHandling/DataHandler/SlugUniqueTest.php

 $dataHandler = GeneralUtility::makeInstance(DataHandler::class);
//$dataHandler->enableLogging = false;
 $dataHandler->start(
            [
                'pages' => [
                    3 => [
                        'title' => 'Page One',
                        'slug' => 'page-one',
                    ],
                ],
            ],
            []
);
$dataHandler->process_datamap();

---

in gridelements:

 $data = [];
$data['tt_content']['NEW234134'] = $dataArray;

$this->getTceMain()->start($data, []);
$this->getTceMain()->process_datamap();