closureInfo: write a doc comment (#391079)

# This derivation builds two files containing information about the

# closure of 'rootPaths': $out/store-paths contains the paths in the

# closure, and $out/registration contains a file suitable for use with

# "nix-store --load-db" and "nix-store --register-validity

# --hash-given".

{

  stdenvNoCC,

  coreutils,

  jq,

}:

/**

  Produces metadata about the closure of the given root paths.

  1. Total NAR size in `$out/total-nar-size`.

  2. Registration, suitable for `nix-store --load-db`, in `$out/registration`.

     Can also be used with `nix-store --register-validity --hash-given`.

  3. All store paths for the closure in `$out/store-paths`.

  # Inputs

  `rootPaths` ([Path])

  : List of root paths to include in the closure information.

  # Type

  ```

  closureInfo :: { rootPaths :: [Path]; } -> Derivation

  ```

  # Examples

  :::{.example}

  ## `pkgs.closureInfo` usage example

  ```

  pkgs.closureInfo {

    rootPaths = [ pkgs.hello pkgs.bc pkgs.dwarf2json ];

  }

  =>

  «derivation /nix/store/...-closure-info.drv»

  ```

  :::

*/

{ rootPaths }:

assert builtins.langVersion >= 5;