Fix link

Author: jyn514

library/core/src/num/error.rs

@@ -54,7 +54,7 @@ impl From<!> for TryFromIntError {
 ///
 /// Among other causes, `ParseIntError` can be thrown because of leading or trailing whitespace
 /// in the string e.g., when it is obtained from the standard input.
-/// Using the [`str.trim()`] method ensures that no whitespace remains before parsing.
+/// Using the [`str::trim()`] method ensures that no whitespace remains before parsing.
 ///
 /// # Example
 ///