mathlib3

6ac19b46 - doc(algebra/ring/basic): change pullback and injective to pushforward and surjective (#6487)

doc(algebra/ring/basic): change pullback and injective to pushforward and surjective (#6487) Zulip reference: https://leanprover.zulipchat.com/#narrow/stream/113489-new-members/topic/pullback.20vs.20pushforward