doc: document development workflow

Author: adrienjoly

README.md

@@ -17,3 +17,29 @@ Note: Version number is bumped and the extension is published to Chrome Web Stor
 This Chrome Extension is open source and free to use. It includes features and fixes proposed by several [contributors](https://github.com/adrienjoly/chrome-next-step-for-trello/graphs/contributors). Pull requests are welcome, especially on prioritized [bugs and feature requests](https://github.com/adrienjoly/chrome-next-step-for-trello/projects/1). Please don't forget to read [CONTRIBUTING.md](CONTRIBUTING.md) first.
 
 [Donations](https://adrienjoly.com/donate) are not expected but always appreciated. 🤗
+
+## Development workflow
+
+### Setup the project locally
+
+```sh
+$ git clone https://github.com/adrienjoly/chrome-next-step-for-trello.git
+$ cd chrome-next-step-for-trello
+$ nvm use # switches to the version of Node.js specified in the .nvmrc file
+$ npm install # installs development dependencies
+$ npm run verify # checks for errors and code style inconsistencies
+```
+
+### Open the local version of the extension
+
+1. In Chrome (or other Chromium-based web browser), open the following URL in a new tab: `chrome://extensions`
+1. Enable the "developer mode"
+1. If Next Step for Trello is already installed, disable it from that list
+1. Click on "Load unpacked extension", then select the `chrome-next-step-for-trello` directory where you setup the project
+1. Go to a Trello board, to make sure that the extension works
+1. Otherwise, check the page's JavaScript console for errors
+1. After every change, don't forget to click the "refresh" icon of the local extension, from `chrome://extensions`
+
+### Release a new version on Chrome Web Store
+
+This process is automated, as specified in `.github/workflows/ci.yml`.