Clarify connections between PCI card and arena #35
Description
Currently the information is split between https://reiserlab.github.io/Modular-LED-Display/docs/g4_acquisition.html (the image) and https://reiserlab.github.io/Modular-LED-Display/docs/g4_assembly.html#connect-arena. Related information is also at https://reiserlab.github.io/Modular-LED-Display/docs/g4_off-the-shelf.html
Make the documentation more consistent.