docs: replace `class variable` with property
docs: replace `class variable` with property

kenjis/CodeIgniter4,bcit-ci/CodeIgniter4,kenjis/CodeIgniter4,bcit-ci/CodeIgniter4,kenjis/CodeIgniter4,bcit-ci/CodeIgniter4,bcit-ci/CodeIgniter4,kenjis/CodeIgniter4,bcit-ci/CodeIgniter4,kenjis/CodeIgniter4