Make line drawings on docs consistent with AP styling

[Michael-Grover]

Discussion 🗣

We can replace the line drawings on the docs page with images that are more consistent with the Accord Project branding.

I could image files that match these illustrations found across the AP websites:

[Michael-Grover]

@mttrbrts when you have a chance, can I have the permissions to add labels and assignees to issues so I can tag them appropriately? I'd also like to assign this issue to @jesswang-dev