doc: better readme

README.md

@@ -4,7 +4,55 @@
 
 > Template project for writing node package with napi-rs.
 
-## Requirement
+## Install this test package
+
+```
+yarn add @napi-rs/package-template
+```
+
+## Support matrix
+
+> ⚠️ Linux musl has not been supported now.
+
+### Operating Systems
+
+| Linux | macOS | Windows x64 MSVC |
+| ----- | ----- | ---------------- |
+| ✓     | ✓     | ✓                |
+
+### NodeJS
+
+| Node10 | Node 12 | Node14 |
+| ------ | ------- | ------ |
+| ✓      | ✓       | ✓      |
+
+## Ability
+
+### Build
+
+After `yarn build/npm run build` command, you can see `index.[darwin|win32|linux].node` file in project root. This is the native addon built from [lib.rs](./src/lib.rs).
+
+### Test
+
+With [ava](https://github.com/avajs/ava), run `yarn test/npm run test` to testing native addon. You can also switch to another testing framework if you want.
+
+### CI
+
+With github actions, every commits and pull request will be built and tested automatically in [`node@10`, `node@12`, `@node14`] x [`macOS`, `Linux`, `Windows`] matrix. You will never be afraid of the native addon broken in these platforms.
+
+### Release
+
+Release native package is very difficult in old days. Native packages may ask developers who use its to install `build toolchains` like `gcc/llvm` , `node-gyp` or something more.
+
+With `Github actions`, we can easily prebuild `binary` for major platforms. And with `N-API`, we should never afraid of **ABI Compatible**.
+
+The other problem is how to deliver prebuild `binary` to users. Download it in `postinstall` script is a common way which most packages do it right now. The problem of this solution is it introduced many other packages to download binary which has not been used by `runtime codes`. The other problem is some user may not easily download the binary from `github/CDN` if they are behind private network (But in most case, they have a private NPM mirror).
+
+In this package we choose a better way to solve this problem. We release different `npm packages` for different platform. And add it to `optionalDependencies` before release the `Major` package to npm.
+
+`NPM` will choose which native package should download from `registry` automatically. You can see [npm](./npm) dir for details. And you can also run `yarn add @napi-rs/package-template` to see how it works.
+
+## Develop requirements
 
 - Install latest `Rust`
 - Install `NodeJS@8.9+` which supported `N-API`