add onnxruntime installation and usage to README

@@ -4,3 +4,38 @@ See <https://github.com/k2-fsa/sherpa>
 
 This repo uses [onnxruntime](https://github.com/microsoft/onnxruntime) and
 does not depend on libtorch.
+
+
+# Onnxruntime Installation
+```
+git clone --recursive --branch v1.12.1 https://github.com/Microsoft/onnxruntime
+cd onnxruntime
+./build.sh \
+    --config RelWithDebInfo \
+    --build_shared_lib \
+    --build_wheel \
+    --skip_tests \
+    --parallel 16
+cd build/Linux/RelWithDebInfo
+sudo make install
+export LD_LIBRARY_PATH=/path/to/onnxruntime/build/Linux/RelWithDebInfo:$LD_LIBRARY_PATH
+```
+
+# Usage
+```
+git clone https://github.com/k2-fsa/sherpa-onnx
+cd sherpa-onnx
+mkdir build
+cd build
+cmake -DONNXRUNTIME_ROOTDIR=/path/to/onnxruntime \
+      -DKALDI_NATIVE_IO_INSTALL_PREFIX=/path/to/kaldi_native_io ..
+make
+./bin/sherpa-onnx path/to/encoder.onnx \
+                  path/to/decoder.onnx \
+                  path/to/joiner.onnx \
+                  path/to/joiner_encoder_proj.onnx \
+                  path/to/joiner_decoder_proj.onnx \
+                  path/to/tokens.txt \
+                  greedy \
+                  path/to/audio.wav
+```