Update docs (#44)

README.md

@@ -14,7 +14,7 @@ released yet (alpha stage for now), some modifications were made to help impleme
 ## Features
 * HelmRequest and Release CRD, namespace based
 * ChartRepo CRD
-* Multi cluster support based on [https://github.com/kubernetes/cluster-registry](https://github.com/kubernetes/cluster-registry)
+* Multi cluster support based on [cluster-registry](https://github.com/kubernetes/cluster-registry)
 * Dependency check for HelmRequest (between HelmRequests)
 * `valuesFrom` support: support to ConfigMap or Secret value store
 * `kubectl apply` like resource manipulation: no more resource conflict and CRD management issues
@@ -52,10 +52,12 @@ For the detailed explain and advanced usage, please check the documentation belo
 ## Documention
 
 * [How captain works](./docs/captain.md)
-* [HelmRequest CRD](./docs/helmrequest.md)
-* [Release CRD](./docs/release.md)
-* [ChartRepo CRD](./docs/chartrepo.md)
-* [Chart CRD](./docs/chart.md)
+* CRDs explain
+  * [HelmRequest CRD](./docs/helmrequest.md)
+  * [Release CRD](./docs/release.md)
+  * [ChartRepo CRD](./docs/chartrepo.md)
+  * [Chart CRD](./docs/chart.md)
+* [Multi-Cluster Support](./docs/multi-cluster.md)
 
 
 ## SDK

docs/multi-cluster.md

@@ -0,0 +1,43 @@
+# Multi Cluster
+
+Multi is an optional but import feature for captain.It's based on the [cluster-registry](https://github.com/kubernetes/cluster-registry), which introduce a CRD called `Cluster`. So If you have `Cluster` in you current kubernetes env(where captain deployed to), captain will watch the clusters and sync HelmRequest for them.
+
+## How Captain Discover Clusters
+`Captain` have a command line args called `--cluster-namespace`, which specified the namespace captain will look up into to find `Cluster` resources.
+
+## Deploy a HelmRequest to a Remote Cluster
+If `.spec.clusterName` is not empty, and it's a valid cluster name, captain will deploy this HelmRequest to the target cluster. For example:
+
+```yaml
+apiVersion: app.alauda.io/v1alpha1
+kind: HelmRequest
+metadata:
+  name: nginx-ingress
+  namespace: default
+spec:
+  chart: stable/nginx-ingress
+  namespace: default
+  clusterName: "cluster1"
+  values:
+    env: prod
+```
+
+In the above example, `Captain` will deploy this HelmRequest to `cluster1`. In this scenario, the generated `Release` and resources will exist in `cluster`, but `HelmRequest` exist in current cluster.
+
+
+## Deploy a HelmRequest to All Clusters
+If `.spec.installToAllClusters` is `true`, Captain will deploy the HelmRequest to all the clusters it knows.
+
+```yaml
+apiVersion: app.alauda.io/v1alpha1
+kind: HelmRequest
+metadata:
+  name: nginx-ingress
+  namespace: default
+spec:
+  chart: stable/nginx-ingress
+  namespace: default
+  installToAllClusters: true
+  values:
+    env: prod
+```