Update release version

Author: hangyan

charts/captain/Chart.yaml

@@ -1,4 +1,4 @@
 name: captain
 appVersion: "2.0"
-version: v2.2-b.2
+version: v0.8.0
 description: A Helm3 Controller

charts/captain/values.yaml

@@ -13,4 +13,4 @@ global:
   images:
     captain:
       repository: alaudapublic/captain
-      tag: v2.2-b.2
+      tag: v0.8.0

docs/install.md

@@ -34,9 +34,5 @@ helm install \
 ``` bash
 helm repo add alauda https://alauda.github.io/charts
 kubectl create namespace captain # or choose a namespace you likes， just remember to update the args below
-helm install  --name=captain --version=v2.2-b.2 --namespace=captain --set namespace=captain alauda/captain
+helm install  --name=captain --version=v0.8.0 --namespace=captain --set namespace=captain alauda/captain
 ```
-
-About the versions, this project has an jenkins pipeline which target on internal purpose usage. 
-It will tag master commits, so there will be a lot of tags. For now there is only one stable version
-`v2.2-b.2` which is well tested. This workflow will changed ASAP.