docs: replace `composer install` with `composer update`
docs: replace `composer install` with `composer update`

composer warns if use `install`:
No composer.lock file present. Updating dependencies to latest instead of installing from lock file. See https://getcomposer.org/install for more information.

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