update comments

client/client.go

@@ -2,6 +2,22 @@
 The client package provides a method to make synchronous, asynchronous and
 streaming requests to services. By default json and protobuf codecs are
 supported.
+
+	import "github.com/micro/go-micro/client"
+
+	c := client.NewClient()
+
+	req := c.NewRequest("go.micro.srv.greeter", &greeter.Request{
+		Name: "John",
+	})
+
+	rsp := &greeter.Response{}
+
+	if err := c.Call(context.Background(), req, rsp); err != nil {
+		return err
+	}
+
+	fmt.Println(rsp.Msg)
 */
 package client