Rendering Core: customise Heading Level depth for Table of Contents

[sean-freeman]

Describe the bug
Heading Levels in Markdown are up to level 6, which the Pilcrow currently supports up to (the Pilcrow maybe should change to https://materialdesignicons.com/icon/link for consistency with GitHub?).

However the auto-generated page Table of Contents on the left-side menu is static to Heading Level 2. The Chevron Right also confuses the end user, as it suggests the TOC could be expanded to see the lower Heading Levels

[cadavre]

I newly installed wiki.js and this was actually first thing I noticed I want to change. People differ in how they construct their synopsis for article. We should allow to change "default level" as well as allow to customize ToC depth per article.

[regevbr]

I created a PR for it (#1931) and waiting for it to be merged

[austinwbest]

Hopefully it is not an issue to ask for an update @NGPixel as it is assigned to you. It has had a PR for a year, simply looking for the thought process on it.

Thanks.

[gurureddy239]

Waiting for the PR to get approved

[MacBadger]

This is the only single issue, that keeps me looking elsewhere and contemplating moving before my internal wiki content gets too large