[doc] Updated dart.dev web repo link

This is my first contribution to Open-Source so go easy on me :P

Closes https://github.com/dart-lang/sdk/pull/45032
https://github.com/dart-lang/sdk/pull/45032

GitOrigin-RevId: d2d816ace491861f27036695763e631f8c3c5580
Change-Id: I7c02794eb328aa27c7b9fb5772fadef138ee22e0
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/185306
Reviewed-by: Vyacheslav Egorov <vegorov@google.com>
diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index 0d6142e..a508ebd 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -11,7 +11,7 @@
       click that icon to report a bug on the page.
     * To report an API doc bug,
       [create an SDK issue](https://github.com/dart-lang/sdk/issues/new?title=API%20doc%20issue:).
-  * Contribute to the Dart developer websites such as [dart.dev](https://dart.dev) (repo: [dart-lang/site-www](https://github.com/dart-lang/site-www)) and [dart.dev/web](https://dart.dev/web) (repo: [dart-lang/site-webdev](https://github.com/dart-lang/site-webdev)). For more information, see [Writing for Dart and Flutter websites](https://github.com/dart-lang/site-shared/wiki/Writing-for-Dart-and-Flutter-websites).
+  * Contribute to the Dart developer websites such as [dart.dev](https://dart.dev) (repo: [dart-lang/site-www](https://github.com/dart-lang/site-www)) and [dart.dev/web](https://dart.dev/web) (repo: [dart-lang/site-www/src/web](https://github.com/dart-lang/site-www/tree/master/src/web)). For more information, see [Writing for Dart and Flutter websites](https://github.com/dart-lang/site-shared/wiki/Writing-for-Dart-and-Flutter-websites).
   * Improve the API reference docs at [api.dart.dev](https://api.dart.dev) by editing doc comments in the [Dart SDK repo](https://github.com/dart-lang/sdk/tree/master/sdk/lib). For more information on how to write API docs, see [Effective Dart: Documentation](https://dart.dev/guides/language/effective-dart/documentation).
 
 ## Before you contribute