Rollup merge of rust-lang#67005 - andrewbanchich:master, r=joshtriplett

capitalize Rust

Capitalize "Rust" in docs.

src/libcore/sync/atomic.rs

@@ -27,7 +27,7 @@
 //!
 //! Atomic variables are safe to share between threads (they implement [`Sync`])
 //! but they do not themselves provide the mechanism for sharing and follow the
-//! [threading model](../../../std/thread/index.html#the-threading-model) of rust.
+//! [threading model](../../../std/thread/index.html#the-threading-model) of Rust.
 //! The most common way to share an atomic variable is to put it into an [`Arc`][arc] (an
 //! atomically-reference-counted shared pointer).
 //!