more complete navigation / preventing orphaned pages

[tmchartrand]

We should make sure that all pages are accessible in a small number of clicks from the sidebar - do we want all pages to fall into a category there, or perhaps just the core ones, with other subpages linked from a landing page for each category? Either way we should add reminders to PRs to check on accessibility.

We could also consider a comprehensive autogenerated navigation tree.

[tmchartrand]

most importantly, link to the glossary!

[dougollerenshaw]

@tmchartrand, can I assign to you?

[tmchartrand]

I can maybe take this on, but should get input from @dbirman first since I think he devised the basic organization, and @dyf since it looks like he made a significant restructuring at some point.

[dbirman]

@tmchartrand I think you can go ahead and restructure and add me as a reviewer?