Swap out images with revised diagrams

[rachelwhitton]

Updated diagrams

[pantheon-decoupled[bot]]

:zap: Deployed with Pantheon Decoupled

This build was successfully deployed with Pantheon. You can track the build logs here.

:eyes: Preview: https://pr-9075-documentation.appa.pantheon.site :hammer_and_wrench: Manage in Pantheon: https://dashboard.pantheon.io/site/2b30153f-e8b1-4427-b076-6109e704ba5d/overview

[stevector]

hmmm, the gradients in this transparent pngs don't look good on the white background?? https://pr-9075-documentation.appa.pantheon.site/certification/study-guide/create

[rachelwhitton]

Reviewed with @stevector on zoom, opt'ing to close this one