add TOC links or TOC navigation

[VladimirAlexiev]

It's very hard to orient yourself in a large ontology document, and to jump to another key place (the 3 indexes).

• LODE has links "back to ToC" or "Object Property ToC" (respectively "Class ToC", "Data Property ToC"). Example from: http://rawgit2.com/euBusinessGraph/eubg-data/master/ontology/_old/index.html (Missing info from ontology doc euBusinessGraph/eubg-data#18)

• I don't quite like the look (far right side), and the functionality is limited (it lets you jump but not orient yourself), but it's much better than nothing
• Some other TOC gadget could be better, eg a sidebar that shows in bold where you are

[nicholascar]

I've added a couple of links like LODE had - for the fragment URI of the Class/Property and a back to Class/Property Index.

Perhaps a left menu, collapsible TOC gadget like the W3C's reSpec docs have would be nice but I'm not sure I can do the necessary styling and JavaScript for that any time soon.

I'd love any offers of assistance for this task!

[nicholascar]

Added a whole ToC in 3.0.0, see https://rdflib.dev/pyLODE/examples/ontdoc/agrif.html