[Addon kubevela#603] Add Apache Spark as a experimental addon

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

experimental/addons/spark-kubernetes-operator/README.md

@@ -67,26 +67,22 @@ vela show spark-application
 
 # Example for how to run a component typed spark-cluster in application
 
-1. Firstly, create a new namespace:
+1. Secondly, copy the following example to "spark-app-v1.yaml":
 
-```
-kubectl create ns spark-cluster
-```
-
-2. Secondly, copy the following example to "spark-app-v1.yaml":
+> The addon will create a namespace named "spark-cluster"
 
 ```
 apiVersion: core.oam.dev/v1beta1
 kind: Application
 metadata:
   name: spark-app-v1
-  namespace: vela-system
+  namespace: spark-cluster
 spec:
   components:
-  - name: my-spark-component
-    type: spark-cluster
+  - name: my-spark-application-component
+    type: spark-application
     properties:
-      name: my-spark-cluster
+      name: my-spark-app
       namespace: spark-cluster
       type: Scala
       mode: cluster