improve wording

Author: RalfJung

library/core/src/cmp.rs

@@ -64,12 +64,15 @@ use self::Ordering::*;
 /// Note that the `B: PartialEq<A>` (symmetric) and `A: PartialEq<C>`
 /// (transitive) impls are not forced to exist, but these requirements apply
 /// whenever they do exist.
-/// The requirement for transitive chains has a subtle consequence: if a crate `a` with type `A`
-/// importing types `B1`, `B2` from another crate `b` defines instances of both `A: PartialEq<B1>`
-/// and `B2: PartialEq<A>`, then if `b` adds a `B1: PartialEq<B2>` implementation in the future that
-/// could create new violations of transitivity. Effectively, crate `a` is making `B1` and `B2`
-/// comparable even though `b` does not permit comparing them. Crate `a` should generally refrain
-/// from doing that to avoid the potential for such conflicts.
+/// The requirement for transitive chains has a subtle consequence: consider a crate `alpha`
+/// defining type `A1` and `A2`, and a crate `beta` defining a type `B`. If `beta` uses `alpha` as a
+/// dependency and provides trait implementations for both `A1: PartialEq<B>` and `B:
+/// PartialEq<A2>`, the transitivity rules don't apply, as an implementation `A1: PartialEq<A2>`
+/// does not exist; but at a later point `alpha` could decide to add such a `A1: PartialEq<A2>`
+/// implementation, in a way that would then make `beta`'s traits implementations violate
+/// transitivity. Effectively, `beta` is already making `A1` and `A2` comparable for equality even
+/// though `alpha` does not permit comparing them. Crate `beta` should generally refrain from doing
+/// that to avoid the potential for such conflicts.
 ///
 /// ## Derivable
 ///