Add missing word in XState Store README (#5016)

packages/xstate-store/README.md

@@ -76,7 +76,7 @@ function DonutCounter() {
 
 ## Usage with Immer
 
-XState Store makes it really to integrate with immutable update libraries like [Immer](https://github.com/immerjs/immer) or [Mutative](https://github.com/unadlib/mutative). Pass the `produce` function into `createStoreWithProducer(producer, …)`, and update `context` in transition functions using the convenient pseudo-mutative API:
+XState Store makes it really easy to integrate with immutable update libraries like [Immer](https://github.com/immerjs/immer) or [Mutative](https://github.com/unadlib/mutative). Pass the `produce` function into `createStoreWithProducer(producer, …)`, and update `context` in transition functions using the convenient pseudo-mutative API:
 
 ```ts
 import { createStoreWithProducer } from '@xstate/store';