docs: Updated typo in Quick Start (#168)

Co-authored-by: Lachlan Collins <1667261+lachlancollins@users.noreply.github.com>

Author: nikolovlazar

docs/quick-start.md

@@ -90,7 +90,7 @@ const unmount = double.mount();
 unmount();
 ```
 
-## Previous Deferred Value
+## Previous Derived Value
 
 You can access the previous value of a derived computation by using the `prevVal` argument passed to the `fn` function: