Bootstrap-Flask 3.0.0 version plan

P.S. Just some temp ideas, will use separate issues to track.

Perhaps also:

remove Bootstrap 4, see also Update all code snippets in docs to use Bootstrap 5 #329
add Bootstrap 6 (not yet released but there is already talk about this version by Bootstrap)
an option to still have built-in CSS/JS for offline development
support icons CDN (but also still built-in for offline development)

Navigation Menu