README doc seems to be incorrect. Plus/minus don't adjust simulation speed, they zoom in/out.

[Ben-Fenner]

I've been enjoying this tool for a while. I ran it about a year ago and it changed priorities for me, which was excellent. I'm running it again about a year later and just happened to notice the README documentation for keyboard shortcuts says: (+-) Adjust simulation speed

However those keyboard buttons seem to zoom the display instead. Not sure if the docs need updating, or if the simulation speed keybindings need updating, but there you are.

For now the only way I seem to be able to adjust what feels like the simulation speed seems to be with: (<>) Adjust time scale

Oh yah, I forgot to mention I'm running the latest release version (0.54).

Cheers!