fix(RN): Typo in manual setup header (#13601)

Author: kahest

docs/platforms/react-native/manual-setup/expo.mdx

@@ -54,7 +54,7 @@ yarn add @sentry/react-native
 pnpm add @sentry/react-native
 ```
 
-### Intialize the SDK
+### Initialize the SDK
 
 <OnboardingOptionButtons
   options={[