cut down counterexample prose and adjust punctuation

Author: hkBst

library/core/src/slice/mod.rs

@@ -1099,12 +1099,11 @@ impl<T> [T] {
     /// assert!(iter.next().is_none());
     /// ```
     ///
-    /// Because the [Iterator] trait cannot represent the required lifetimes, there is no `windows_mut` analog to `windows`.
-    /// (If there was, then `[0,1,2].windows_mut(2).collect()` would create 2 mutable references
-    /// to the middle element of that array, which would violate [the rules of references],
-    /// though a [LendingIterator] analog is possible.)
-    /// However, you can sometimes use [`Cell::as_slice_of_cells`](crate::cell::Cell::as_slice_of_cells) in
-    /// conjunction with `windows` to accomplish something similar:
+    /// Because the [Iterator] trait cannot represent the required lifetimes, there is no `windows_mut` analog to `windows`;
+    /// `[0,1,2].windows_mut(2).collect()` would violate [the rules of references]
+    /// (though a [LendingIterator] analog is possible).
+    /// You can sometimes use [`Cell::as_slice_of_cells`](crate::cell::Cell::as_slice_of_cells) in
+    /// conjunction with `windows` instead:
     ///
     /// [the rules of references]: https://doc.rust-lang.org/book/ch04-02-references-and-borrowing.html#the-rules-of-references
     /// [LendingIterator]: https://blog.rust-lang.org/2022/10/28/gats-stabilization.html