Streamlining the setup process.

- dependency version pinning
- automatic `secret_key` generation
- automatic config file generation
- installing `once` script
- setup instructions in README.md
- adding an architecture diagram

requirements.txt

@@ -1,12 +1,12 @@
 -e .
-aws_cdk.core
-aws_cdk.aws_apigatewayv2
-aws_cdk.aws_certificatemanager
-aws_cdk.aws_cloudformation
-aws_cdk.aws_dynamodb
-aws_cdk.aws_events
-aws_cdk.aws_events_targets
-aws_cdk.aws_lambda
-aws_cdk.aws_logs
-aws_cdk.aws_route53
-aws_cdk.aws_s3
+aws_cdk.core>=1.45
+aws_cdk.aws_apigatewayv2>=1.45
+aws_cdk.aws_certificatemanager>=1.45
+aws_cdk.aws_cloudformation>=1.45
+aws_cdk.aws_dynamodb>=1.45
+aws_cdk.aws_events>=1.45
+aws_cdk.aws_events_targets>=1.45
+aws_cdk.aws_lambda>=1.45
+aws_cdk.aws_logs>=1.45
+aws_cdk.aws_route53>=1.45
+aws_cdk.aws_s3>=1.45