[idobe]

The author looks to be Japanese, so that's probably why. In Japan, grade school teachers often use the symbols like so:

○ = correct × = incorrect △ = partially incorrect

I'd prefer the yes, no, partial though as well.

[kevincox]

Ah, thanks for explaining that.

However yes, for an English README it probably makes sense to stick to words to clear any confusion.

[goccy]

I fixed it ! Thanks !