Update readme

README.md

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 # kibertas
-Kubernetes E2E 
+
+kibertas is a CLI tool for achieving end-to-end (E2E) testing of Kubernetes environments. However, it does not perform E2E testing of the Kubernetes core itself.
+
+Specifically, at the moment, it supports E2E testing of the following tools necessary for Kubernetes operations:
+
+- [cluster autoscaler](https://github.com/kubernetes/autoscaler/tree/master/cluster-autoscaler)
+- Ingress
+    - [aws-load-balancer-controller](https://kubernetes-sigs.github.io/aws-load-balancer-controller/v2.6/)
+- [ExternalDNS](https://github.com/kubernetes-sigs/external-dns)
+- [cert-manager](https://cert-manager.io/)
+- [datadog-agent](https://github.com/DataDog/datadog-agent)
+- [fluentd](https://github.com/fluent/fluentd)
+  - with S3 Output
+
+For E2E testing of Kubernetes itself, please refer to the `certified-conformance` of [SONOBUOY](https://sonobuoy.io/) to verify the functionality that a cluster should meet.
+
+Also, this tool is not a plugin for SONOBUOY, but a original implementation.
+
+## Why not use SONOBUOY Plugin?
+
+- Considered SONOBUOY plugin, but it was larger in terms of how to run SONOBUOY itself and how to write plugin.yaml than the simple E2E testing desired by us.
+- Because we wanted to create it.☺️
+
+# How to test locally
+
+You need to start [kind](https://github.com/kubernetes-sigs/kind) in advance and apply ingress-nginx and cert-manager.
+
+```
+$ kind create cluster
+$ make apply-cert-manager
+$ make apply-ingress-nginx
+```
+
+At the moment, not all target tests have been implemented.
+
+# How to execute locallity
+
+Grab the latest binary from [our GitHub releases page](https://github.com/chatwork/kibertas/releases).
+
+Otherwise, you can clone this repository and build it yourself using `make`:
+
+```
+$ make build
+```
+
+Ensure that you have acess to the cluster, by setting `KUBECONFIG` envvar or properly configuring the default kubeconfig.
+
+Now, run `kibertas`.
+
+`kubertas` has sub-commands for respective test targets- For example, to test that the `cert-manager` on your cluster is working, run:
+
+```
+$ ./dist/kibertas test cert-manager
+```
+
+For the complete list of available test targets and the options, run:
+
+```
+$ ./dist/kibertas test help
+```