Fix the solution code for “Using Async Storage”

Also, other minor improvements.

exercise-src/react-native/15-async-storage/01-problem/src/services/storage/storage.ts

@@ -1,6 +1,6 @@
 import AsyncStorage from "@react-native-async-storage/async-storage"
 
-// Exercise: Implement the four `AsyncStorage` helpers in `storage.ts`.
+// Exercise: Implement the four `AsyncStorage` helpers.
 export const getData = async <T>(key: string): Promise<T | undefined> => {}
 
 export const getAllKeys = (): Promise<readonly string[]> => {}

exercise-src/react-native/15-async-storage/01-solution/src/services/pmo/api/api.ts

@@ -63,7 +63,7 @@ export async function apiRequest<
     if (method === "GET" && response.ok) {
       await storeData<CachedResponse<Data>>(keyPrefix + requestUrl, {
         data: data,
-        dateTime: new Date().toDateString(),
+        dateTime: new Date().toJSON(),
       })
     }
 

src/react-native/15-using-asyncstorage/using-asyncstorage.md

@@ -126,17 +126,24 @@ Here are some pointers on implementing this strategy:
 npm install @react-native-async-storage/async-storage@1
 ```
 
-✏️ Update **jest-setup.ts** to be:
+✏️ Terminate the existing dev server and start it again:
 
-@diff ../../../exercises/react-native/14-user-input/01-solution/jest-setup.ts ../../../exercises/react-native/15-async-storage/01-problem/jest-setup.ts only
+```bash
+npm run start
+```
 
-✏️ Create **src/services/storage/index.ts** and update it to be:
+✏️ Update **jest-setup.ts** to be:
 
-@sourceref ../../../exercises/react-native/15-async-storage/01-problem/src/services/storage/index.ts
+@diff ../../../exercises/react-native/14-user-input/01-solution/jest-setup.ts ../../../exercises/react-native/15-async-storage/01-problem/jest-setup.ts only
 
 ✏️ Create **src/services/storage/storage.ts** and update it to be:
 
 @sourceref ../../../exercises/react-native/15-async-storage/01-problem/src/services/storage/storage.ts
+@highlight 3
+
+✏️ Create **src/services/storage/index.ts** and update it to be:
+
+@sourceref ../../../exercises/react-native/15-async-storage/01-problem/src/services/storage/index.ts
 
 ✏️ Update **src/services/pmo/api/api.ts** to be:
 
@@ -166,6 +173,8 @@ You can verify that this is working correctly by using DevTools to:
 - View the requests (or lack thereof) being made.
 - Inspect the stored data.
 
+**Hint:** Use [`new Date().toJSON()`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Date/toJSON) to get the current datetime as a string.
+
 ### Solution 1
 
 If you’ve implemented the solution correctly, the tests will pass when you run `npm run test`!
@@ -249,6 +258,7 @@ We’ll assume that the data is version `1` if we haven’t stored the version n
 ✏️ Create **src/services/DataMigration/DataMigration.tsx** and update it to be:
 
 @sourceref ../../../exercises/react-native/15-async-storage/02-problem/src/services/DataMigration/DataMigration.tsx
+@highlight 13, 21-23, only
 
 ✏️ Create **src/services/DataMigration/index.ts** and update it to be: