Hi @pickfire, can you take the time to explain why this change makes sense?

The title field is metadata for lowdown so we can't remove it. It would be nice if it didn't appear in the HTML manual but there is no easy way to do that.

Isn't something like

---
title: nix-env
---

a thing people do in markdown for this?

That's called front matter, and yeah, it's a thing.

I'm still wondering if this pull request is a product of the hacktoberfest.

Huh? Oh, I forgot yesterday when I send this hactoberfest already started (I do want to do hacktoberfest but I bet 4 pulls are easy). No, it wasn't because of hacktoberfest, I was just browsing nix docs and I noticed this weird thing in nix-env https://nixos.org/manual/nix/unstable/command-ref/nix-env.html, looks like it is also there for nix-build but I don't see this in all pages.

Okay, I didn't know this is part of frontmatter since they usually have --- so I thought it was part of failed migration to new unstable docs. Should I change it to ---?

By the way, happy mid-autumn festival (yesterday)! :D