hwdef: add annotated layout/wiring diagram for FlywooF745 v3

[mbuzdalov]

This is a minor addition of a missing picture for the v3 of the FlywooF745 AIO flight controller.

The picture is made by sticking together two pictures from the official docs and by annotating where RX/TX is shown relative to either FC or peripherals (which swaps these). The latter was done because I misread these diagrams on my first try.

(I am aware that there is a similar picture in the docs already, but we seem to keep pictures more or less in sync or in hwdef, and I tend to go to hwdef anyway when setting up the craft because of the DMA-related information from hwdef files.)