fix: typo within README

Fixing a tiny typo in the README

Author: agebhardt

README.md

@@ -6,7 +6,7 @@
 
 Passkey Flex provides passkey support for existing authentication systems. It abstracts the complexities of native passkey APIs and provides a simple, clean solution to take your authentication to the next level.
 
-Use the `passage-flex-react-native` SDK in your React Native app to implement passkey registration, authentication, or additinal step-up or multifactor authentication (MFA).
+Use the `passage-flex-react-native` SDK in your React Native app to implement passkey registration, authentication, or additional step-up or multifactor authentication (MFA).
 
 For full documentation, including setting up a backend SDK, visit the [Passkey Flex documentation here](https://docs-v2.passage.id/flex).