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







leanprover-community/mathlib,leanprover-community/mathlib