Update README.md

Author: lentil1016

README.md

@@ -1,2 +1,20 @@
+[![CircleCI](https://circleci.com/gh/lentil1016/descheduler.svg?style=svg)](https://circleci.com/gh/lentil1016/descheduler)
+
 # descheduler
-A descheduler server for kubernetes cluster
+A descheduler server for kubernetes cluster. 
+
+This scheduler run as a server, and it makes evicting decisions more "gentlely". 
+
+Every time it assess resource status of the cluster and evicts certain number of pods(defined by `spec.rules.maxEvictSize` in config file),  waits for replica sets pods of which is evicted rebounded to fully ready, then reassess the cluster and evicting again.
+
+It says you can get the nutrition you need from either food or pills, and this descheduler is the food, [kubernetes-incubator/descheduler](https://github.com/kubernetes-incubator/descheduler) is the pills.
+
+## Feature
+
+- Run as a server, not a job.
+- Triggered deschedule by node ready event or by timer.
+- Config node selector to limit the nodes descheduler will affect.
+- Be able to deschedule:
+  - the pods that can find prefered node
+  - the pods with peer pods(pods created by the same SeplicaSet) on the same node
+  - the pods with peer pods in cluster