terraform-docs: 0.9.1 -> 0.11.2

[snoord]

Motivation for this change

0.9.1 has been out of date for a while now, so this change brings
terraform-docs inline with the current version 0.11.2.

The owner of the repository has changed from segmentio to terraform-docs
since the last pull request.

This commit also introduces the use of buildGoModule in place of
buildGoPackage, so that we can avoid generating a deps.nix file for
module dependencies.

Things done

• Tested using sandboxing (nix.useSandbox on NixOS, or option sandbox in nix.conf on non-NixOS linux)
• Built on platform(s)
  • NixOS
  • macOS
  • other Linux distributions
• Tested via one or more NixOS test(s) if existing and applicable for the change (look inside nixos/tests)
• Tested compilation of all pkgs that depend on this change using nix-shell -p nixpkgs-review --run "nixpkgs-review wip"
• Tested execution of all binary files (usually in ./result/bin/)
• Determined the impact on package closure size (by running nix path-info -S before and after)
• Ensured that relevant documentation is up to date
• Fits CONTRIBUTING.md.

[SuperSandro2000]

A deps.nix file (generated from vgo2nix) has also been added for use
with the goDeps argument of buildGoPackage, as terraform-docs would not
build without it.

Can we use buildGoModule instead?

[snoord]

A deps.nix file (generated from vgo2nix) has also been added for use
with the goDeps argument of buildGoPackage, as terraform-docs would not
build without it.

Can we use buildGoModule instead?

This didn't even occur to me tbh, I'm sure it's possible. I'll give it a go :)