add example: invert dictionary 2

[polyxord]

Here's an alternative way to invert a dictionary.

I didn't want to update the existing example since this new way only takes one less keystroke, and I think that there's learning value in seeing both ways of doing things.

It is a bit redundant to have a different file for the same scenario, so I would understand if you don't want to add this.

[nik-rev]

Thanks, I think it's cool to have multiple ways to do the same thing as long as each offers a unique approach