Update CONTRIBUTING.md

CONTRIBUTING.md

@@ -42,6 +42,7 @@ The `develop` branch is the development branch which means it contains the next
 1. Push: Push your `trunk` branch to GitHub (e.g. `git push origin trunk`).
 1. [Compare](https://github.com/10up/safe-svg/compare/trunk...develop) `trunk` to `develop` to ensure no additional changes were missed.
 1. Test the pre-release ZIP locally by [downloading](https://github.com/10up/safe-svg/actions/workflows/build-release-zip.yml) it from the Build release zip action artifact and installing it locally. Ensure this zip has all the files we expect, that it installs and activates correctly and that all basic functionality is working.
+1. Either perform a regression testing utilizing the available [Critical Flows](https://10up.github.io/Open-Source-Best-Practices/testing/#critical-flows) and Test Cases or if [end-to-end tests](https://10up.github.io/Open-Source-Best-Practices/testing/#e2e-testing) cover a significant portion of those Critical Flows then run e2e tests.  Only proceed if everything tests successfully.
 1. Release: Create a [new release](https://github.com/10up/safe-svg/releases/new), naming the tag and the release with the new version number, and targeting the `trunk` branch. Paste the changelog from `CHANGELOG.md` into the body of the release and include a link to the [closed issues on the milestone](https://github.com/10up/safe-svg/milestone/#?closed=1).
 1. SVN: Wait for the [GitHub Action](https://github.com/10up/safe-svg/actions/workflows/wordpress-plugin-deploy.yml) to finish deploying to the WordPress.org repository. If all goes well, users with SVN commit access for that plugin will receive an emailed diff of changes.
 1. Check WordPress.org: Ensure that the changes are live on [WordPress.org](https://wordpress.org/plugins/safe-svg/). This may take a few minutes.