doc: Update readme to make it looks better

Signed-off-by: jwcesign <[email protected]>

README.md

@@ -1 +1,23 @@
-# playground
+# Karmada Playground Scenarios
+
+Karmada (Kubernetes Armada) is a Kubernetes management system that enables you to run your cloud-native applications across multiple Kubernetes clusters and clouds, with no changes to your applications. By speaking Kubernetes-native APIs and providing advanced scheduling capabilities, Karmada enables truly open, multi-cloud Kubernetes.
+
+So in order to let users try and learn Karmada with an interactive online environment, Karmada provide different scenarios on different platforms.
+
+## Available platforms
+
+You can enjoy tutorial experience about Karmada with following platforms.
+
+### Killercoda platform
+
+![killercoda-platform](./images/killercoda-platform.png)
+
+* Try [Installing Karmada on Kubernetes through the Karmada CLI](https://killercoda.com/karmada/scenario/karmada-CLI-installtion-example).
+* Try [Propagate workload through karmada duplicated mode](https://killercoda.com/karmada/scenario/karmada-HA-workload-example1).
+* Try [Propagate workload through karmada divided mode](https://killercoda.com/karmada/scenario/karmada-HA-workload-example2).
+* Try [Simulate multitype cluster failover through Karmada](https://killercoda.com/karmada/scenario/karmada-Failover-example).
+
+
+## Contribution
+
+If you know of any excellent online interactive platforms, we welcome any pull requests to adapt the scenarios to the new platform.