Update doc for integration test

tests/integration/README.md

@@ -1,25 +1,18 @@
 ## Integration Testing
+Integration test verifies the functionality of EBS CSI driver as a standalone server outside Kubernetes. It exercises the lifecycle of the volume by creating, attaching, staging, mounting volumes and the reverse operations. And it verifies data can be written onto an EBS volume without any issue.
 
-### Requirements 
+## Run Integration Tests Locally
+The integration test is executed using [aws-k8s-tester](https://github.com/aws/aws-k8s-tester) which is CLI tool for k8s testing on AWS. With aws-k8s-tester, it automates the process of provisioning EC2 instance, pulling down and building EBS CSI driver, running the defined integration test and sending test result back. See aws-k8s-tester for more details about how to use it.
 
-1. macOS or Linux
-1. `GOPATH` environment variable [set](https://github.com/golang/go/wiki/SettingGOPATH)
-1. [AWS account](https://aws.amazon.com/account/) that has been [configured locally](https://docs.aws.amazon.com/cli/latest/userguide/cli-chap-configure.html)
+### Requirements
+1. AWS credential is [configured](https://docs.aws.amazon.com/cli/latest/userguide/cli-chap-configure.html)
+1. Other requirements needed by aws-k8s-tester
 
-Must satisfy also the requirements for `aws-ebs-csi-driver`
-
-### Run Integration Tests Locally
-
-```bash
+```
 make test-integration
 ```
 
 #### Overriding Defaults
 - The master branch of `aws-ebs-csi-driver` is used by default. To run using a pull request for `aws-ebs-csi-driver`, set `PULL_NUMBER` as an environment variable with a value equal to the pull request number.
 
-- When the tests are run, a new VPC is created by default. To run using an existing VPC, set `AWS_K8S_TESTER_VPC_ID` as an environment variable with a value equal to an existing VPC ID.
-
-### Additional Information
-
-- GitHub [repo](https://github.com/aws/aws-k8s-tester) for `aws-k8s-tester`, which includes information about releases and running locally
-- Kubernetes Enhancement Proposal ([KEP](https://github.com/kubernetes/enhancements/blob/master/keps/sig-aws/20181126-aws-k8s-tester.md)) for `aws-k8s-tester`
+- When the tests are run, a new VPC is created by default. To run using an existing VPC, set `AWS_K8S_TESTER_VPC_ID` as an environment variable with a value equal to an existing VPC ID. This will be useful when VPC limit is reached in the region under test.