fix remaining heading level issues

Author: katiegoines

src/fragments/lib-v1/in-app-messaging/integrate-your-application/integrate-your-application.mdx

@@ -16,7 +16,7 @@ import js1 from '/src/fragments/lib-v1/in-app-messaging/integrate-your-applicati
 
 <Fragments fragments={{  javascript: js1 , angular: js1, nextjs: js1, react: js1, vue: js1 }} />
 
-### Integrate In-App Messaging
+## Integrate In-App Messaging
 
 Amplify UI provides a Higher-Order Component for ease of integrating the In-App Messaging UI with your application. Simply wrap your application root component in, for example, `App.js`.
 

src/fragments/lib-v1/react-native-polyfills.mdx

@@ -1,4 +1,4 @@
-### Install Amplify and its dependencies
+## Install Amplify and its dependencies
 
 ```bash
 npm install aws-amplify@^5 amazon-cognito-identity-js @react-native-community/netinfo @react-native-async-storage/async-storage react-native-get-random-values react-native-url-polyfill

src/pages/[platform]/build-a-backend/storage/copy-files/index.mdx

@@ -92,7 +92,7 @@ Future<void> copy() async {
 }
 ```
 
-### More `copy` options
+## More `copy` options
 
 Option | Type | Description |
 | -- | -- | ----------- |