Fix the TOC being loaded as last making the content jump around with big pages

[bedroesb]

New reversed approach: The assumption is that there will be a TOC, and if not enough H2 headings, the full width will be taken for content.

Some other changes:

• The default minimum of 1 headings for TOC to show up (instead of 2)
• More documentation
• RDMkit linkage example

IMPORTANT: to prevent the TOC from visibly disappearing when not needed, add the toc: false attribute to the page.

This will close #216