docs: update solution, usage and advanced

README.md

@@ -1,5 +1,28 @@
 # Keyframe Reducer In Unity
 
+## Solution
+
+Read the animation curve into several tracks, each track compressed independently.
+
+First, all components of the same variable are combined and stored in the IKeyframeBase implementation.
+
+Then, for each curve, determine whether each keyframe can be interpolated by the two keyframes before and after it, and if so, this frame can be deleted.
+
+## Usage
+
+You can check the scripts under the Editor folder for some examples.
+
+The only interface is 
+
+```csharp
+KeyframeReducer reducer = new KeyframeReducer();
+reducer.ReduceKeyframes(clip, rotationError, positionError, scaleError, checkData);
+```
+
+## Advanced
+
+You can easily derive curve classes of other data types and compress them by implement `IKeyframeBase<T>` and `AnimationCurveBase<T>`, and then add an error function to KeyframeReducer.
+
 ## Result
 
 Model source: https://github.com/fish-ken/unity-animation-compressor
@@ -11,6 +34,8 @@ Model source: https://github.com/fish-ken/unity-animation-compressor
 | Skill | 446.3 | 415.0 |
 | Walk | 78.1 | 74.8 |
 
+Error Rate: 0.5%
+
 ## Reference
 
 - https://www.bzetu.com/344/.html