Fixes broken link

Author: samejr

docs/migrating-from-v3.mdx

@@ -140,7 +140,7 @@ export const myAiTask = schemaTask({
 });
 ```
 
-We've replaced the `toolTask` function with the `ai.tool` function, which creates an AI tool from an existing `schemaTask`. See the [ai.tool](#ai-tool) section for more details.
+We've replaced the `toolTask` function with the `ai.tool` function, which creates an AI tool from an existing `schemaTask`. See the [ai.tool](/tasks/schemaTask#ai-tool) page for more details.
 
 ## Breaking changes