Delete the nodejs-training.png file

[bmuenzenmeyer]

https://github.com/nodejs/nodejs.org/blob/main/public/static/images/nodejs-training.png is no longer used and can be deleted. This git repository hosted on GitHub tracks changes to all files- added, deleted, or modified, so we can always recover it if needed.

You can use the GitHub UI or your personal fork to delete the file.

Open a pull request back to the https://github.com/nodejs/nodejs.org repository to complete the task.

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