I want to like this having used regular `git diff` tool with colours, but this is just too busy.
As a bit of feedback, you might wish to put a section showing how to make a git alias for diffr, to complement the section on how to install it as the default. I know how to do this already, because I use delta and dft depending on what I need to see, but it would be useful to others to have a copy-paste solution handy.