Fix javaweb example

The image used for the init container runs /mv.sh, which executes `tail
-f /etc/hosts` as its last command. Since this command will block
forever, an explicit command should be specified for this container that
just copies the sample war file to /app (otherwise the pod will get
stuck forever, waiting for the init container to succeed).

staging/javaweb-tomcat-sidecar/javaweb.yaml

@@ -6,6 +6,7 @@ spec:
   initContainers:
     - image: resouer/sample:v1
       name: war
+      command: ["sh", "-c", "cp /sample.war /app"]
       volumeMounts:
         - mountPath: /app
           name: app-volume