Fixing many link syntaxes in doc comments

sdk/lib/io/io.dart

Index: sdk/lib/io/io.dart
diff --git a/sdk/lib/io/io.dart b/sdk/lib/io/io.dart
index aea1b5b1de4c1fa546a50f5fdd71c46a39bb4a77..04cc6f2425525f555992ff3b8896c660b72cb1d9 100644
--- a/sdk/lib/io/io.dart
+++ b/sdk/lib/io/io.dart
@@ -186,13 +186,11 @@
  *
  * ## Other resources
  *
- * For an introduction to I/O in Dart, see the
- * [dart:io section of the library tour]
- * (https://www.dartlang.org/docs/dart-up-and-running/contents/ch03.html#ch03-dartio---file-and-socket-io-for-command-line-apps).
+ * For an introduction to I/O in Dart, see the [dart:io section of the library
+ * tour](https://www.dartlang.org/docs/dart-up-and-running/ch03.html#dartio---io-for-command-line-apps).
  *
- * To learn more about I/O in Dart, refer to the
- * [tutorial about writing command-line apps]
- * (https://www.dartlang.org/docs/tutorials/io/).
+ * To learn more about I/O in Dart, refer to the [tutorial about writing
+ * command-line apps](https://www.dartlang.org/docs/tutorials/io/).
  */
 library dart.io;