Now we only have the api reference which only describes apis: https://alibaba.github.io/jsni/2.2/html/jsni_8h.html
We also need specification or documentation which include not only api reference, but also the detailed usage and explain of jsni.

The documentation may be like the JNI or node-addon's N-API documentation:
https://docs.oracle.com/javase/8/docs/technotes/guides/jni/spec/jniTOC.html
https://nodejs.org/api/n-api.html#n_api_n_api