When I've done it, I've done it as a status log at the bottom of the README, or in a separate file in the project. But I think your level of detail is just righ

When I've done it, I've done it as a status log at the bottom of the README, or in a separate file in the project. But I think your level of detail is just right: it doesn't look ridiculously time consuming, and yet it captures the real content & momentum of the project.