[Feature Request] Create Class, Interface and Enums as expanders in the TOC for .NET Documentation about docfx

[filzrev]

The proposed implementation is as follows.

• Add categoryLayout option to metadata section.
• If "categoryLayout": "nested" option is enabled.
  Reorganize TOC structure as described at #9933 (comment).

If there seems to be no particular problems. I'll create PR later.

Config document to be added

---

categoryLayout

Specifies how categories in TOC are organized:

• flattened (default): Renders namespaces as a plain label.
• nested: Renders category in a nested tree form.

Note

This setting is is available when using ApiPage or Markdown output format. mref format don't support categories.

[yufeih]

We could incorporate this change if there is sufficient interest. Please upvote if you find this useful.

[UmaHarano]

What is the best way to Upvote? In this issue or in the original discussion thread?

[UmaHarano]

Also, I want to also add that -
when I use outputFormat = apiPage, my custom template is not being used. I lose the ability to customize the site with my template (partial files, main.js, etc).
If there is a workaround for this, please let me know.