Fix doc tests for trim_right_matches

Author: Arzte

src/liballoc/str.rs

@@ -1734,7 +1734,7 @@ impl str {
     /// A more complex pattern, using a closure:
     ///
     /// ```
-    /// assert_eq!("1fooX".trim_left_matches(|c| c == '1' || c == 'X'), "fooX");
+    /// assert_eq!("1fooX".trim_right_matches(|c| c == '1' || c == 'X'), "fooX");
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
     pub fn trim_right_matches<'a, P: Pattern<'a>>(&'a self, pat: P) -> &'a str