Unalias Blank and white from greyscale

BUR #31017 has been rejected.

remove alias black_and_white -> greyscale

Let's see where this takes us.
According to the greyscale wiki, images only depicting black and white aren't meant to be tagged with greyscale, but it is nonetheless aliased.
So, we have two options:

1. Unalias black_and_white from greyscale
or
2. remove that clause from the wiki (which was actually done fairly recently)

The clause was added by @tapnek here. When it was discussed on Discord I don't recall there being a specific reason mentioned as to why it was added, and it's frankly a completely stupid clause. That said, maybe there's value of a tag for 1-bit monochrome images, but it'd need to be different from black and white since people generally use that to refer to greyscale in terms of media.

I was trying to think of a case where monochrome would apply but not greyscale. The latter may imply the former, but it feels in practice as if every monochrome image is greyscale.

The bulk update request #31017 (forum #305392) has been rejected by @nonamethanks.

tapnek said:
The latter may imply the former, but it feels in practice as if every monochrome image is greyscale.

This is wrong. "monochrome" means a single color in the image (aside from black and white). Look at something like red_theme monochrome or blue_theme monochrome and you'll find plenty of cases of non-greyscale monochrome pics.