I registered a project for the webpage and the fpm-docs at weblate: Fortran programming language @ Hosted Weblate and will apply there to get free hosting for our open source projects.
Translations can be submitted via the web interface and will than result in a PR opened by weblate at the respective repository. Here is one created for the fpm-docs: Translations update from Hosted Weblate by weblate · Pull Request #65 · fortran-lang/fpm-docs · GitHub, as you can see the attribution for the translation is also preserved.
Let me know what you think or if you encounter any issues.