remove imodelhub and other superfluous docs

[ben-polinsky]

[ben-polinsky]

@calebmshafer @aruniverse I've removed the pages referenced in Michelle's spreadsheet. Removed some links to aforementioned pages but not sure if some the links should stay with altered urls.

[ben-polinsky]

@calebmshafer forgot about this one. Good to publish or more to do?

[calebmshafer]

@calebmshafer forgot about this one. Good to publish or more to do?

@ben-polinsky more to do still. I made a bunch of updates but I think we're still missing some important iModel information with the Hub stuff removed. I'll see if I can take another pass this week on it.