Johannes Hoppe contributed to the prettier/angular-html-parser repository by updating documentation to reflect new support for regular expressions in Angular templates introduced in Angular v21. He focused on aligning developer guidance with the latest framework capabilities, removing outdated restrictions from best-practices materials to streamline onboarding and reduce support queries. His work involved careful revision of Markdown documentation, application of Angular and TypeScript knowledge, and collaboration through git-based workflows. While the contribution was limited to a single feature over one month, it demonstrated attention to detail and ensured that project documentation remained accurate and helpful for both new and existing users.