explain linting and node version in CONTRIBUTING.md

CONTRIBUTING.md

@@ -1,14 +1,14 @@
 Contributing to action-setup-vim
 ================================
 
-Thank you for contributing to [action-setup-vim][proj]. This document is for development.
+Thank you for contributing to [action-setup-vim][repo]. This document is for development.
 
 ## Testing
 
 For testing validation for inputs and outputs, run unit tests:
 
-```
-$ npm run test
+```sh
+npm run test
 ```
 
 Tests for installation logic are done in [CI workflows][ci] in E2E testing manner. All combinations
@@ -17,6 +17,20 @@ of inputs are tested on the workflows triggered by `push` and `pull_request` eve
 After building and running `action-setup-vim` action, the workflow verifies the post conditions
 with [post_action_check.ts](./scripts/post_action_check.ts).
 
+## Linting
+
+In addition to type checking with TypeScript compiler, the following command checks the sources with
+[eslint][] and [pretteir][].
+
+```sh
+npm run lint
+```
+
+## Node.js version
+
+Node.js version must be aligned with Node.js runtime in GitHub Actions. Check the version at
+`runs.using` in [action.yml](./action.yml) and use the same version for development.
+
 ## How to create a new release
 
 When releasing v1.2.3:
@@ -33,6 +47,8 @@ When releasing v1.2.3:
 [Post-release check workflow][post-release] runs to check released `rhysd/action-setup-vim@v1` action.
 The workflow runs when modifying `CHANGELOG.md` and also runs on every Sunday 00:00 UTC.
 
-[proj]: https://github.com/rhysd/action-setup-vim
-[ci]: https://github.com/rhysd/action-setup-vim/actions?query=workflow%3ACI
+[repo]: https://github.com/rhysd/action-setup-vim
+[ci]: https://github.com/rhysd/action-setup-vim/actions/workflows/ci.yml
+[eslint]: https://eslint.org/
+[prettier]: https://prettier.io/
 [post-release]: https://github.com/rhysd/action-setup-vim/actions?query=workflow%3A%22Post-release+check%22+branch%3Amaster