Add a way to show functions and packages from any flake in noogle.

**Is your feature request related to a problem? Please describe.** A clear and concise description of what the problem is. Ex. I'm always frustrated when [...] Im always annoyed trying to find documentation for command and packages in flakes that are not nixpkgs. Noogle currently only exposes docs and functions for nixpkgs only. I think it would be a cool direction to take this project in if support was added to take flake inputs and output the noogle page for those inputs allowing you to search and view docs for arbitrary flakes **Describe the solution you'd like** Some sort of option on the website, or in a command line tool to take all flake inputs and generate the noogle.dev page locally, taking inspiraton from `rustdoc` in its usage **Describe alternatives you've considered** Ive considered rolling my own tool for this but it would be duplicated work and not be as widely used as if it was in a widely used tool like noogle