Update to version v2.1.0

Author: groverlalit

CONTRIBUTING.md

@@ -23,7 +23,7 @@ reported the issue. Please try to include as much information as you can. Detail
 ## Contributing via Pull Requests 
 Contributions via pull requests are much appreciated. Before sending us a pull request, please ensure that: 
 
-1. You are working against the latest source on the *master* branch. 
+1. You are working against the latest source on the *main* branch. 
 2. You check existing open, and recently merged, pull requests to make sure someone else hasn't addressed the problem already. 
 3. You open an issue to discuss any significant work - we would hate for your time to be wasted. 
 
@@ -55,7 +55,7 @@ If you discover a potential security issue in this project we ask that you notif
 
 
 ## Licensing 
-See the [LICENSE](https://github.com/awslabs/aws-control-tower-customizations/blob/master/LICENSE.txt) file for our project's licensing. We will ask you to confirm the licensing of your contribution. 
+See the [LICENSE](https://github.com/awslabs/aws-control-tower-customizations/blob/main/LICENSE.txt) file for our project's licensing. We will ask you to confirm the licensing of your contribution. 
 
 
 We may ask you to sign a [Contributor License Agreement (CLA)](http://en.wikipedia.org/wiki/Contributor_License_Agreement) for larger changes. 

README.md

@@ -86,4 +86,4 @@ This solution collects anonymous operational metrics to help AWS improve the qua
 
 ## License
 
-See license [here](https://github.com/awslabs/aws-control-tower-customizations/blob/master/LICENSE.txt) 
+See license [here](https://github.com/awslabs/aws-control-tower-customizations/blob/main/LICENSE.txt)