Rollup merge of rust-lang#76221 - camelid:cleanup-iter-for, r=jyn514

Clean up header in `iter` docs for `for` loops

@rustbot modify labels: T-doc

library/core/src/iter/mod.rs

@@ -135,7 +135,7 @@
 //! methods like `nth` and `fold` if an iterator can compute them more efficiently without calling
 //! `next`.
 //!
-//! # for Loops and IntoIterator
+//! # `for` loops and `IntoIterator`
 //!
 //! Rust's `for` loop syntax is actually sugar for iterators. Here's a basic
 //! example of `for`: