Auto merge of rust-lang#6298 - JohnTitor:fix-example, r=llogiq

Fix `await_holding_refcell_ref` examples for clarify

- Remove redundant `()`
- Fix variable name

changelog: none

clippy_lints/src/await_holding_invalid.rs

@@ -65,8 +65,8 @@ declare_clippy_lint! {
     /// use std::cell::RefCell;
     ///
     /// async fn foo(x: &RefCell<u32>) {
-    ///   let b = x.borrow_mut()();
-    ///   *ref += 1;
+    ///   let mut y = x.borrow_mut();
+    ///   *y += 1;
     ///   bar.await;
     /// }
     /// ```
@@ -77,8 +77,8 @@ declare_clippy_lint! {
     ///
     /// async fn foo(x: &RefCell<u32>) {
     ///   {
-    ///     let b = x.borrow_mut();
-    ///     *ref += 1;
+    ///      let mut y = x.borrow_mut();
+    ///      *y += 1;
     ///   }
     ///   bar.await;
     /// }