Don't be afraid of building a product specification, and doing it in Markdown and auto-generating a mini-website out of it.
Just build a product specification for how the product works (which is useful documentation), not how the product will work (which is waterfall).
We're experimenting with this a little, and I'm getting into document-driven development a little: if the product spec is in markdown, why not create a pull request on it as part of your story/project planning that shows the changes that would happen as a consequence of your work. Once the story is done, you can merge the pull request, even. We're not quite there with this yet, but I'm optimistic.
Just build a product specification for how the product works (which is useful documentation), not how the product will work (which is waterfall).
We're experimenting with this a little, and I'm getting into document-driven development a little: if the product spec is in markdown, why not create a pull request on it as part of your story/project planning that shows the changes that would happen as a consequence of your work. Once the story is done, you can merge the pull request, even. We're not quite there with this yet, but I'm optimistic.
Putting design assets into your repo is also acceptable, and also paying time and attention to commit messages can be really, really helpful. I love this talk, for example: https://brightonruby.com/2018/a-branch-in-time-tekin-suleyma...