Improve UX when user put a wrong value

[finnp]

Setting the value for the first time is nice, but if you want to change it afterwards e.g. because you messed it up, it's a bit hard to change. (You would need to find the config file delete it and run the program again.)

I'm thinking about providing default args like --help, --reset and --config

--help would just point people to reset and config
--reset would reset all settings
--config would show a path to a file that can be edited (see #1)