Link to the correct page for async execution

Author: matthewp

docs/guides.md

@@ -9,5 +9,5 @@ These guides are meant to help you along your journey learning Finite State Mach
 
 * __[Composition](./guides/composition.html)__: How to use functional composition when building state machines, to maximize code reuse where possible.
 * __[Nested States](./guides/nested-states.html)__: Create machines with nested states by [invoking](./api/invoke.html) other machines.
-* __[Awaiting asynchronous completion](./guides/awaiting-asynchronous-completion.html)__: How to await a machine to enter a `final` state.
+* __[Awaiting asynchronous completion](./guides/awaiting-asynchronous-execution.html)__: How to await a machine to enter a `final` state.
 * __[Comparison with XState](./guides/comparison-with-xstate.html)__: Differences and tradeoffs between Robot and [XState](https://xstate.js.org).