Hard to navigate to the docs page

**Describe the problem/challenge you have**
When trying to navigate to the docs, I get a 404 at [carvel.dev/ytt/docs/](https://carvel.dev/ytt/docs/). It then only offers me the ability to return to the main carvel.dev site or a "page not found support site".

Instead, the correct link for ytt's docs is
[carvel.dev/ytt/docs/latest](https://carvel.dev/ytt/docs/latest)

**Describe the solution you'd like**
I'd like a simple redirect from `/docs` to `/docs/latest` for all of our tools. I don't think we should need our users to remember "if I want the latest docs I need to explicitly write it." Instead, I think we should make the assumption that not providing a version implies they want the latest docs, and give the user something useable, not a generic "page not found".

Alternatively, I'd like to see a directory of our docs versions if we want to make the assumption that the user doesn't know which version they want.

No file, test, or entry point is named. Start by locating the routing or documentation configuration for the tool sites and verify how an unversioned /docs path is handled. Done means /docs redirects to /docs/latest for all tools, or presents a documentation-version directory, without returning a 404.

Written by the indexing model from the issue text.