Change MindMap to PlantUML

[ashleyfrieze]

This has a couple of benefits:

1. Avoid having to regenerate the .PNG every time the mind map is changed
2. Renders automatically with white background, even in dark mode

See #1358

[ashleyfrieze]

Note: the URL of the mindmap is presently set to this branch on this fork. This is just for illustration. It would need to be set to the master location before merging.

[velo]

That is awesome. Thanks for that

[ashleyfrieze]

@velo thanks for taking it on. I’m a big fan of the open feign library. Delighted to contribute even a tiny amount.