Added billing tool (#646)

Signed-off-by: Pranit <pranitr@amazon.com>

README.md

@@ -2363,6 +2363,7 @@ Billing and Cost Management
 	-	🔹Enable [billing reports](https://docs.aws.amazon.com/awsaccountbilling/latest/aboutv2/detailed-billing-reports.html) and install an open source tool to help manage or monitor AWS resource utilization. [**Teevity Ice**](https://github.com/Teevity/ice) (originally written by Netflix) is probably the first one you should try. Check out [docker-ice](https://github.com/jonbrouse/docker-ice) for a Dockerized version that eases installation.
 	-	🔸One challenge with Ice is that it doesn’t cover amortized cost of reserved instances.
 	-	Other tools include [Security Monkey](https://github.com/Netflix/security_monkey) and [Cloud Custodian](https://github.com/capitalone/cloud-custodian).
+	-	Use [AWS Simple Monthly Calculator](https://calculator.s3.amazonaws.com/index.html) to get an estimate of usage charges for AWS services based on certain information you provide. Monthly charges will be based on your actual usage of AWS services, and may vary from the estimates the Calculator has provided.
 -	**Third-party services:** Several companies offer services designed to help you gain insights into expenses or lower your AWS bill, such as [OpsClarity](http://www.opsclarity.com/), [Cloudability](https://www.cloudability.com/), [CloudHealth Technologies](https://www.cloudhealthtech.com/), and [ParkMyCloud](http://www.parkmycloud.com/). Some of these charge a percentage of your bill, which may be expensive. See the [market landscape](#tools-and-services-market-landscape).
 -	AWS’s [Trusted Advisor](https://aws.amazon.com/premiumsupport/trustedadvisor/) is another service that can help with cost concerns.
 -	Don’t be shy about asking your account manager for guidance in reducing your bill. It’s their job to keep you happily using AWS.