Support for Submenus

[tinyheero]

In rmarkdown (at least v2.10+), there is support for submenus (https://github.com/rstudio/rmarkdown/pull/1426) in rmarkdown website. This doesn't seem to work in distill (v1.2) websites. For instance, consider the following _site.yml:

name: "site"
navbar:
  title: "My Website"
  left:
    - text: "Home"
      href: index.html
    - text: "About"
      href: about.html
      menu:
        - text: "Sub_1"
          href: sub1.html
        - text: "Sub_2"
          menu:
            - text: "Sub_2_below"
              href: sub2.html

And the following index.Rmd:

---
params:
  root_dir: NULL
title: "Distill Website"
description: |
  Scientific and technical writing, native to the web
output:
  distill::distill_article:
    toc: true
    code_folding: true
---

# Home Page

When we render this Rscript --slave -e "rmarkdown::render('index.Rmd')", the index.html has this menu:

The "SUB_2" has no submenu. While if you change the index.Rmd to:

---
params:
  root_dir: NULL
title: "Distill Website"
description: |
  Scientific and technical writing, native to the web
---

# Home Page

such that the output is no longer a distill article, but a rather rmarkdown article then we get this:

.

Is it possible to get support for submenus in distill websites?