Diagram in Upgrade Instructions is Not Readable

[MattDRogers]

Change Type

Cleanup (formatting, typos, etc.)

Area

Installation/upgrade

Proposed Changes

In the documentation for Upgrading Netbox, there is a diagram showing what version you need to be on to upgrade to the next major release.
The background color of the page is so dark that the information on the diagram is unreadable:

If you click on the image, it opens in a new tab where the background color is white and the information is readable:

It would probably be best to make this image readable without having to click on it to open in a new tab, in my opinion.

[bctiemann]

This is actually a much more widespread issue; many of the PNGs in docs are transparent with black text.