Link to Progress spec from Tasks spec

Author: LucaButBoring

docs/specification/draft/basic/utilities/tasks.mdx

@@ -449,7 +449,7 @@ stateDiagram-v2
 
 ### Task Progress Notifications
 
-Task-augmented requests support progress notifications as defined in the progress notification specification. The `progressToken` provided in the initial request remains valid throughout the task's lifetime.
+Task-augmented requests support progress notifications as defined in the [progress](./progress) specification. The `progressToken` provided in the initial request remains valid throughout the task's lifetime.
 
 ### Task Listing