fix static navbar container issues, clean up docs presentation by unfixing the top navbar in favor of static one, start adding table of contents for longer sections of docs

fixes #4044: make z-index of tooltips same as fixed navbar so they overlay it if generated from within

fixes #4444: clarify docs copy that new icon white style is intentional on active and hover links in .nav and .dropdown-menu

fixes #4445: .btn-link shouldn't have a pressed button-like state at all, so nuking everything on :active as well