fix: fixed link to unwrapping; close #502

Author: NataliaTepluhina

src/guide/composition-api-setup.md

@@ -125,7 +125,7 @@ If `setup` returns an object, the properties on the object can be accessed in th
 </script>
 ```
 
-Note that [refs](../api/refs-api.html#ref) returned from `setup` are [automatically unwrapped](../api/refs-api.html#access-in-templates) when accessed in the template so you shouldn't use `.value` in templates.
+Note that [refs](../api/refs-api.html#ref) returned from `setup` are [automatically unwrapped](/guide/reactivity-fundamentals.html#ref-unwrapping) when accessed in the template so you shouldn't use `.value` in templates.
 
 ## Usage with Render Functions