Merge pull request #638 from Musaddiq625/patch-1

Update README.md

flutter_secure_storage/README.md

@@ -57,7 +57,7 @@ This allows us to be able to fetch secure values while the app is backgrounded,
 An example:
 
 ```dart
-final options = IOSOptions(accessibility: IOSAccessibility.first_unlock);
+final options = IOSOptions(accessibility: KeychainAccessibility.first_unlock);
 await storage.write(key: key, value: value, iOptions: options);
 ```