Generate & distribute man pages

Currently if you download Vector debian packages from Vector.dev they don't include man pages.

operator@OBSIDIAN:~/vector$ curl -O https://packages.timber.io/vector/0.7.1/vector-amd64.deb
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100 7381k  100 7381k    0     0  6866k      0  0:00:01  0:00:01 --:--:-- 6866k
operator@OBSIDIAN:~/vector$ sudo dpkg -i vector-amd64.deb 
Selecting previously unselected package vector.
(Reading database ... 37114 files and directories currently installed.)
Preparing to unpack vector-amd64.deb ...
Unpacking vector (0.7.1) ...
Setting up vector (0.7.1) ...
operator@OBSIDIAN:~/vector$ man vector
No manual entry for vector

According to the Debian maintainer guidelines, it's suggested to include these.

It looks like we can generate man pages using something like this (source) in our build.rs.

use clap::IntoApp;
use clap_generate::gen_manuals;

#[path="src/cli.rs"]
mod cli;

fn main() {
    let app = cli::Head::into_app();
    for man in gen_manuals(&app) {
        let name = "head.1";
        let mut out = fs::File::create("head.1").unwrap();
        use std::io::Write;
        out.write_all(man.render().as_bytes()).unwrap();
    }
}

Since this solution is agnostic, we could use this for all packages.

Start by inspecting the CLI entry point in src/cli.rs and the proposed build.rs integration, using the rust-cli man-page generation example as reference. Confirm how generated pages can be included in the Debian package and other packages. Done means installing the vector-amd64.deb and successfully opening the Vector manual with man vector.