Renamed the good first issue label for rustbot
Renamed the good first issue label for rustbot

See https://rust-lang.zulipchat.com/#narrow/stream/257328-clippy/topic/Rename.20the.20.22good.20first.20issue.22.20label.20for.20bot.20usage/near/220428018

aidancully/rust,aidancully/rust,graydon/rust,graydon/rust,aidancully/rust,graydon/rust,aidancully/rust,graydon/rust,graydon/rust,aidancully/rust,aidancully/rust,graydon/rust