Publish node-addon-api wrapper for sherpa-onnx as npm packages (#829)

scripts/node-addon-api/README.md

@@ -1,3 +1,23 @@
 # Introduction
 
 This folder contains `node-addon-api` wrapper for `sherpa-onnx`.
+
+Caution: This folder is for developer only.
+
+## Usage
+
+```bash
+git clone https://github.com/k2-fsa/sherpa-onnx
+cd sherpa-onnx
+mkdir build
+cd build
+cmake -DCMAKE_INSTALL_PREFIX=./install -DBUILD_SHARED_LIBS=ON ..
+make -j install
+export PKG_CONFIG_PATH=$PWD/install:$PKG_CONFIG_PATH
+cd ../scripts/node-addon-api/
+
+./node_modules/.bin/node-gyp build --verbose
+
+# see test/test_asr_streaming_transducer.js
+# for usages
+```