README.md needs updating

The installation and configuration instructions in README.md require updating for more recent versions of mame, which apparently require the roms to be installed in ~/.mame or perhaps somewhere else for globally-available images.

glomming onto this, the current README.MD says to use F1 and F2 to open the UI Menu, but on Windows it's still F1 and TAB, which is causing issues.

I see F1-Tab is also true for (my Intel Sonoma-based) Mac.