Update "Dimension Settings Overview" to reflect new margin/padding UI

[mrfoxtalbot]

Issue Description

A) This is what the margin & padding interface look like right now:

B) This is going to look like once 6.3 is released.

URL of the Page with the Issue

https://wordpress.org/documentation/article/dimension-controls-overview/

Section of Page with the issue

This update affects the entire article (and possibly other articles).

Why is this a problem?

The screenshots and directions on how to use this feature will be outdated.

Suggested Fix

Update the article.

[femkreations]

Refer #973

[mrfoxtalbot]

Thank you, @femkreations
I see that #973 is completed so I will mark this issue as solved.