Add support for BS ScrollSpy to show active TOC entry

[chalin]

• Proposed solution for New Feature: Navigation indication on the right TOC #349
• Adds support for Bootstrap's Scrollspy for the right-side TOC nav
• Adds an "On this page" title/heading for the TOC. I'm unsure about this, but wanted to test it out. Please give me your feedback.
• Fixes a spacing issue with TOC being too close to page meta links. (I was sure I had an issue open for that but I can't find it.)

Previews

• https://deploy-preview-2287--docsydocs.netlify.app/docs/
• https://deploy-preview-2287--docsydocs.netlify.app/blog/2024/year-in-review/

Screenshot

[MarkvanMents]

Looks nice.
I don't particularly like the On this page - our solution is to have the document title at the top with an href to take the reader all the way to the top of the document.

We also don't have the selected line indented, we just add the bar to the left and add bold.
But would be nice to have this OOTB in Docsy.

[chalin]

Thanks for the feedback @MarkvanMents, and the proposal. Let's continue the discussion about the TOC heading via:

• TOC heading as "On this page" or something else? #2288