All browsers

Run npm run build for the desired browser

Chrome

https://developer.chrome.com/webstore/publish

Upload chrome.zip to https://chrome.google.com/webstore/developer/dashboard

Firefox

https://developer.mozilla.org/en-US/Add-ons/Distribution

Upload firefox.zip to https://addons.mozilla.org/en-US/developers/addon/submit/1

Opera

https://dev.opera.com/extensions/publishing-guidelines/

Upload chrome.zip to https://addons.opera.com/developer/