fix: revisit gui help messages

[yucongalicechen]

This looks good. I recommend we work a bit on the argparse helps so they are more readable when they are in the gui.

Do we have docs? Some of the longer explanations can go to the docs if we have them. Or is there a way to have them longerin in the cli but shorter in the gui? That could work too.

For the top input, in the gui it is not so helpful a name for the variable. maybe data_sets or something is more descriptive.

Originally posted by @sbillinge in #196 (comment)