Fix the method host-provides-host-config name in readme to correct name host-provides-user-config

[mariolopjr]

Very small spelling fix. Noticed an error in the README for the following code snippet:

# modules/routes.nix
{ den, ... }:
let
  noop = _: { };

  by-platform-config = { host }:
    vix.${host.system} or noop;

  user-provides-host-config = { user, host }:
    vix.${user.aspect}._.${host.aspect} or noop;

  host-provides-host-config = { user, host }:
    vix.${host.aspect}._.${user.aspect} or noop;

  route = locator: { user, host }@ctx: 
    (locator ctx) ctx;
in 
{
  den.aspects.routes.__functor = 
    den.lib.parametric true;
  den.aspects.routes.includes = 
    map route [
      user-provides-host-config
      host-provides-user-config
      by-platform-config
    ];
}

The method in this example is host-provides-host-config, but should be host-provides-user-config; the second host should be user.

[Copilot]

Pull Request Overview

This PR corrects a naming inconsistency in the README documentation. The function name host-provides-host-config has been renamed to host-provides-user-config to accurately reflect that it provides configuration for the user aspect (as evidenced by the function accessing user.aspect in its return value), not the host aspect.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[vic]

Thank you!

I've been tempted not to use code examples in the README as they are not checked (all our code in template/default IS checked). But at the same time, I want the README to provide a way for people to know how to use den. So, maybe the examples in README have runtime failures, thanks for checking a fixing.