update readme

README.md

@@ -7,4 +7,30 @@ EventRetriever is a gitee event spider for datacache.
 ![](http://assets.processon.com/chart_image/6163e23e0791290cc7819291.png)
 
 #### Domain Model
-![](http://assets.processon.com/chart_image/616428d163768921fa176b05.png)
+![](http://assets.processon.com/chart_image/616428d163768921fa176b05.png)
+
+#### How to contribute
+If you’re interested in contributing code, the best starting point is to have a look at our Gitee issues to see which tasks are the most urgent. 
+
+Sunmao accepts PR's (pull requests) from all developers.
+
+Issues can be submitted by anyone - either seasoned developers or newbies.
+
+#### Installation
+
+- **Step 1** Setting up the k8s environment, Google GKE or minikube or microk8s are ok for deployment.
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+- **Step 2** Setting up webhook url in gitee projects, in order to receive issue event requests from you project.
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+- **Step 3** Setting up `api_url` and `gitee_token` environment variables.
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+- **Step 4** Using Dockerfile to build docker image and then upload it to DockerHub.
+
+- **Step 5** Deploy the project by yaml on k8s.
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