Add explanatory image for setting the focal area of an image

The current documentation for setting the focal area of an image is helpful, but it would be even more useful if there was an explanatory image to accompany the instructions.

This would make it easier for users to understand how to set the focal area and ensure that they are doing it correctly.

Suggested solution is to add an image to the documentation that shows the steps for setting the focal area of an image. The image should include a visual representation or a three second video of how to drag the marquee around the most significant element of the image. This will help users understand the feature and ensure that they are setting the focal area correctly.