chore: update pre-reqs and getting started

src/pages/[platform]/build-a-backend/auth/customize-auth-lifecycle/custom-auth-flows/index.mdx

@@ -732,7 +732,7 @@ The Auth category can be configured to perform a [custom authentication flow](ht
 
 ## Prerequisites
 
-Amplify requires a minimum target platform for iOS (13.0), Android (API level 24), and macOS (10.15). Additional setup is required for some target platforms. Please see the [platform setup](/[platform]/build-a-backend/auth/connect-your-frontend/sign-in/#platform-setup) for more details on platform specific setup.
+Amplify requires a minimum target platform for iOS (13.0), Android (API level 24), and macOS (10.15). Refer to [Flutter's supported deployment platforms](https://docs.flutter.dev/reference/supported-platforms) when targeting Web, Windows, or Linux. Additional setup is required for some target platforms. Please see the [platform setup](/[platform]/build-a-backend/auth/connect-your-frontend/sign-in/#platform-setup) for more details on platform specific setup.
 
 ## Configure Auth
 

src/pages/[platform]/start/quickstart/index.mdx

@@ -1296,6 +1296,7 @@ Before you get started, make sure you have the following installed:
 - [git](https://git-scm.com/) v2.14.1 or later
 - You will also need to [create an AWS Account](https://portal.aws.amazon.com/billing/signup). Note that AWS Amplify is part of the [AWS Free Tier](https://aws.amazon.com/amplify/pricing/).
 - Configure your AWS account to use with Amplify [instructions](/[platform]/start/account-setup/).
+- A stable version of [Flutter](https://docs.flutter.dev/get-started/install).
 
 <Callout info>
 You can follow the [official documentation](https://flutter.dev/docs/get-started/install) to install Flutter on your machine and check the [editor documentation](https://docs.flutter.dev/get-started/editor) for setting up your editor.