Update README.md

Author: bluet

README.md

@@ -6,12 +6,12 @@ Support **wildcard**, **nested**, and **filter_function** in *template*.
 ~~~~ js
 "use strict";
 
-var objectFilter = require('obj-filter');
+var objFilter = require('obj-filter');
 
 var template = {
     "runtime": {
         "connectionState": undefined,
-        "powerState": function () {return "HELLOWORLD"},
+        "powerState": function (args) {return "HELLOWORLD " + args},
         "bootTime": "my boot time",
         "paused": false,
         "snapshotInBackground": 1111111
@@ -36,15 +36,34 @@ var data = function_or_somewhere();
 //};
 
 
-var result = objectFilter(template, data);
+var result = objFilter(template, data);
 
 // result is:
-// {
-//    "runtime": {
-//        "powerState": "HELLOWORLD",
-//        "bootTime": "2017-04-20T13:56:19.377Z",
-//        "paused": false,
-//        "snapshotInBackground": true
-//    }
-// };
+{
+   "runtime": {
+       "powerState": "HELLOWORLD poweredOn",
+       "bootTime": "2017-04-20T13:56:19.377Z",
+       "paused": false,
+       "snapshotInBackground": true
+   }
+};
 ~~~~
+
+## Template Object
+According to the **Template Object structure**, `obj-filter` supports the following types of value with different behaviour to build the result object.
+
+### undefined
+If the *value* of the key is `undefined`, the key will be **filtered** (skipped) and will not included in result object.
+
+### object
+If the *value* of the key is an `object`, `obj-filter` will _dive into it and check the **deeper** level of keys_.  
+
+### function
+If the *value* of the key is an `function`, `obj-filter` will _pass the **value** of the same key in **input data** to the **function**_, and includes it's returned data in result.  
+So it's your call to customize how you would like to handle, define what you want to do with the input data. Be sure to **return something** from your function.
+
+- If return `undefined`, the key will be **filtered** (skipped).
+- If return anything else, the key will be **included**.
+
+### Anything else (string, integer, `true`, `false`, etc)
+The value of the key will be **included**.