Add document for support array result

Author: ningyougang

README.md

@@ -62,6 +62,43 @@ pub fn main(args: Value) -> Result<Value, Error> {
 
 The action is mainly composed by a `main` function that accepts a JSON `serdes Value` as input and returns a `Result` including a JSON `serde Value`.
 
+For the return result, not only support `A JSON serde Value` but also support `Array serde Value`
+
+So a simple `hello array` funtion would be:
+
+```rust
+extern crate serde_json;
+
+use serde_derive::{Deserialize, Serialize};
+use serde_json::{Error, Value};
+
+
+pub fn main(args: Value) -> Result<Value, Error> {
+    let output = ["a", "b"];
+    serde_json::to_value(output)
+}
+```
+
+And support array result for sequence action as well, the first action's array result can be used as next action's input parameter.
+
+So the function can be:
+
+```rust
+extern crate serde_json;
+
+use serde_derive::{Deserialize, Serialize};
+use serde_json::{Error, Value};
+
+
+pub fn main(args: Value) -> Result<Value, Error> {
+    let inputParam = args.as_array();
+    let defaultOutput = ["c", "d"];
+    match inputParam {
+        None => serde_json::to_value(defaultOutput),
+        Some(x) => serde_json::to_value(x),
+    }
+}
+```
 ### Managing dependencies
 
 If your action needs external dependencies, you need to provide a zip file including your source, and your cargo file with all your dependencies. The folder structure is the following: