Request to PR: Add AWS set of guides

[mtliendo]

Hey! Last month I tweeted out a missing part about converting a JWK to a PEM. I have a separate PR coming to fix that, but it got me thinking about other ways I could contribute.

I'd like to offer up the following AWS guides:

1. How to create a user in DynamoDB after a user signs up with Clerk
2. How to authorize your Clerk users to access your AWS AppSync API
3. How to authorize your Clerk users to access your API Gateway
4. How to use RBAC to allow your Clerk users to access their Amazon S3 bucket

I feel those 4 guides would allow customers to confidently use Clerk as an alternative to Amazon Cognito and make use of various social providers that Cognito doesn't support out of the box.

Thoughts? Happy to elaborate on any of the above topics or discuss alternatives as well.