Document filter categories for replace.py

[hle0]

Right now, filter categories (accessed with the -f option) cannot be shown from the command line; instead, you have to read the in-code documentation. There should be a -f help or -f list switch on replace.py, or some other form of documentation.

[aidenrosen]

This would be a good thing to add. I hate reading documentation

[jjtheall]

I agree. Being able to access the documentation from the command line would help speed up user input if they forget a command.

[LittleTealeaf]

I also agree that there should be some more documentation on these sorts of things, perhaps bundle this up and add a published manual page for the terminal use