Update README.md

Author: mrousavy

README.md

@@ -101,7 +101,7 @@ console.log(`Fibonacci Result: ${result}`)
 ## What's possible?
 
 * You can use variables from "outside" (e.g. state), but those will be immutable/frozen.
-* You can use functions from "outside" if they also contain the `'worklet'` directive.
+* You can use functions from "outside". If they also contain the `'worklet'` directive they can be called synchronously, otherwise they have to be dispatched to the JS thread by using `runOnJS`.
 * You can assign Reanimated Shared Values.
 * You can call native JSI functions ("Host Functions") from a JSI library, e.g. every function [react-native-mmkv](https://github.com/mrousavy/react-native-mmkv#usage) provides.
 * You can asynchronously dispatch calls to functions from "outside" using `runOnJS` from react-native-reanimated.