History of timebase 1 change

In doc/internal/vdp-vram-timing/cpu-arbitration-model.py, lines 260–271 on main. Every change that wrote or deleted one of these lines, or deleted a line from between them. Exact, because each line keeps its identity across edits; edits elsewhere in the file are not here. Also: oxy log -L 260,271:doc/internal/vdp-vram-timing/cpu-arbitration-model.py.