add readme

README.md

@@ -1,6 +1,13 @@
 # ofxOnnxRuntime
 [ONNX Runtime](https://github.com/microsoft/onnxruntime) tiny wrapper for openFrameworks
 
+!['test'](screenshot.png)
+
+
+## Installation
+- macOS
+    - copy `libonnxruntime.1.10.0.dylib` to `/usr/local/lib` 
+
 ## Tested environment
 - MacBookPro 2018 Intel + macOS Catalina