update documentation

[binary1230]

most user-facing stuff hasn't changed so this isn't too bad but we should touch on:

1. the new XML format
2. probably make a quick video about how to connect bsnes-plus and Diz together for the traceloggin
3. new visuals window

[binary1230]

did some of this for the tracelogging

[blackerking]

For your 3. point:
Maybe an additional donut diagram with percents of data / graphics / empty etc.