Those should be redirected to the api docs, which do exist (although for inject are not quite useful, but inject is pretty much just a wrapped FunctionK). Can you open an issue on github when you find something like this? That helps tracking and fixing it.
A new site is coming up with better docs that the 47 team is working on, in the meantime PRs to improve docs or broken links are welcomed and will be ported over to the new site.