Apply suggestions from code review

Co-authored-by: Oli Scherer <[email protected]>

Author: celinval

compiler/rustc_thread_pool/README.md

@@ -2,12 +2,10 @@ Note: This is an unstable fork made for use in rustc
 
 Rayon-core represents the "core, stable" APIs of Rayon: join, scope, and so forth, as well as the ability to create custom thread-pools with ThreadPool.
 
-Maybe worth mentioning: users are not necessarily intended to directly access rayon-core; all its APIs are mirrored in the rayon crate. To that end, the examples in the docs use rayon::join and so forth rather than rayon_core::join.
+Maybe worth mentioning: users are not necessarily intended to directly access rustc_thread_pool; all its APIs are mirrored in the rayon crate. To that end, the examples in the docs use rayon::join and so forth rather than rayon_core::join.
 
-rayon-core aims to never, or almost never, have a breaking change to its API, because each revision of rayon-core also houses the global thread-pool (and hence if you have two simultaneous versions of rayon-core, you have two thread-pools).
 
 Please see [Rayon Docs] for details about using Rayon.
 
 [Rayon Docs]: https://docs.rs/rayon/
 
-Rayon-core currently requires `rustc 1.63.0` or greater.