It totally depends on the site though. Maybe you want `index.html` to be a
"Welcome to this project, check out this video, or maybe the <documentation?>"
with that last bit being a link to the actual documentation. In this case it
would be super annoying if Nim generated an `index.html` file for you. Naming
the HTML the same as the modules means that you can have things like
`docs/mymodule.html` which is a nice descriptive URL. For your GitHub sites
example maybe run `pandoc` on the README to generate an `index.html` file that
then links to the documentation? Would serve as a nice welcome page and then
take you on to the actual technical documentation for those who wants to read
it.
