The author of this text created a detector for Angular projects using the Netlify CLI's open-source nature and its ability to detect project types. The detector is a single JavaScript file that checks for required files, dependencies, and scripts to determine if it's an Angular project. It returns an object with information about the project, including its type, command, port, proxy port, environment variables, possible arguments, URL regular expression, and distribution folder. To contribute this detector to the Netlify CLI, one needs to fork the repository, create a branch, add the detector file, test it in a local project, commit and push the changes, and submit a pull request following the guidelines. The process involves a few steps, including installing dependencies, setting up a remote repository, creating a new branch, adding the detector file, testing it locally, committing and pushing the changes, and submitting a pull request.