docs: add deleted content from the User Guide
docs: add deleted content from the User Guide

lonnieezell/CodeIgniter4,kenjis/CodeIgniter4,kenjis/CodeIgniter4,lonnieezell/CodeIgniter4,bcit-ci/CodeIgniter4,lonnieezell/CodeIgniter4,ytetsuro/CodeIgniter4,ytetsuro/CodeIgniter4,ytetsuro/CodeIgniter4,ytetsuro/CodeIgniter4,samsonasik/CodeIgniter4,ytetsuro/CodeIgniter4,kenjis/CodeIgniter4,samsonasik/CodeIgniter4,kenjis/CodeIgniter4,ytetsuro/CodeIgniter4,bcit-ci/CodeIgniter4,bcit-ci/CodeIgniter4,bcit-ci/CodeIgniter4,kenjis/CodeIgniter4,samsonasik/CodeIgniter4,samsonasik/CodeIgniter4,samsonasik/CodeIgniter4,lonnieezell/CodeIgniter4,lonnieezell/CodeIgniter4,lonnieezell/CodeIgniter4,bcit-ci/CodeIgniter4,samsonasik/CodeIgniter4