Update README.md

thx! @chitoku-k

Author: 0V

README.md

@@ -1,17 +1,32 @@
 # RxVRTK
-Extensions for converting all VRTK event to UniRx stream
 
-Extension scripts are [here](https://github.com/0V/RxVRTK/tree/master/Assets/RxVRTK/Scripts/Extensions) .  
+Extensions for converting all the VRTK events to UniRx stream
 
-Release Notes, see [RxVRTK/releases](https://github.com/0V/RxVRTK/releases)
+
+Scripts are [here](https://github.com/0V/RxVRTK/tree/master/Assets/RxVRTK/Scripts).  
+
+For Release Notes and unitypackage, see [RxVRTK/releases](https://github.com/0V/RxVRTK/releases).
 
 ## Dependencies
 * VRTK v3.2.1  
-[GitHub](https://github.com/thestonefox/VRTK)  ,  [Asset Store](https://assetstore.unity.com/packages/tools/vrtk-virtual-reality-toolkit-vr-toolkit-64131)
+[GitHub](https://github.com/thestonefox/VRTK),  [Asset Store](https://assetstore.unity.com/packages/tools/vrtk-virtual-reality-toolkit-vr-toolkit-64131)
 * UniRx  
-[GitHub](https://github.com/neuecc/UniRx)  ,  [Asset Store](https://assetstore.unity.com/packages/tools/integration/unirx-reactive-extensions-for-unity-17276)
+[GitHub](https://github.com/neuecc/UniRx),  [Asset Store](https://assetstore.unity.com/packages/tools/integration/unirx-reactive-extensions-for-unity-17276)
+
+
+## What is RxVRTK?
+
+RxVRTK mediates VRTK (VR Toolkit) and UniRx.  
+
+RxVRTK consists of two components: **Event extensions** and **RxVRTK components**.
+
+### 1. Event extensions
+**Event extensions** provide extension methods to convert an exposed VRTK event such as ```VRTK_ControllerEvents.TriggerPressed``` to an Rx stream.
+
+You can observe ```{EVENT NAME}``` by using ```{EVENT NAME}AsObservable()``` method.
 
-## Usage
+
+### Example: Event Extensions
 
 ``` csharp
 VRTK_ControllerEvents controllerEvents = GetComponent<VRTK_ControllerEvents>();
@@ -23,3 +38,53 @@ controllerEvents.TriggerPressedAsObservable()
     });
 
 ```
+
+Event extensions have a prefix "RxVRTK_" and a suffix "Extension".
+
+  
+### 2. RxVRTK components
+
+**RxVRTK components** provide an event system that registers a callback by its method name and the registered callbacks are automatically called by the event system of VRTK.
+
+An RxVRTK component inherits from VRTK classes and overrides the aforementioned methods so that it converts a VRTK event to Rx stream. When you use these components, you **must not** override such methods and **must** only use observable methods instead.
+
+
+### Note
+
+Let's say you want to register a callback for "StartUsing". In this case, VRTK calls "StartUsing" of an VRTK_InteractableObject instance if it implements a method that matches the following signature:
+
+```csharp
+void StartUsing(VRTK_InteractUse currentUsingObject);
+```
+
+As these methods are already overridden in RxVRTK_InteractableObject, which inherits VRTK_InteractableObject to fire UniRx events and RxVRTK utilizes this technique to register an event callback, ensure that you **do not** use neither "StartUsing" nor `new` to hide this method.
+
+
+### Example: RxVRTK components
+The base class of RxVRTK_InteractableObject is **VRTK_InteractableObject**. This class provides interactive events: StartUsing, StartTouching, Grabbed,  etc.
+
+``` csharp
+using RxVRTK;
+using UniRx;
+using UnityEngine;
+
+public class SomeObject : RxVRTK_InteractableObject
+{
+    protected void Start()
+    {
+        this.StartUsingAsObservable()
+            .Subscribe(user =>
+            {
+                Debug.Log(user.name + " is using this object!");
+            });
+    }
+}
+
+```
+
+
+RxVRTK components have a prefix "RxVRTK_" but no suffix.
+
+
+## License
+This library is released under the [MIT License](https://github.com/0V/RxVRTK/blob/master/LICENSE).