fix link

Author: MaryaBelanger

src/content/language/macros.md

@@ -44,7 +44,6 @@ and a `fromJson` deserialization constructor.
 
 [experiment flag]: /tools/experiment-flags
 [`JsonCodable`]: {{site.pub-pkg}}/json/versions/0.20.0
-{{site.repo.dart.sdk}}/tree/main/pkg/json
 [channel]: https://dart.dev/get-dart#release-channels
 
 ### Set up the experiment