README.md - add `INSTALLATION` section

Signed-off-by: Pang Yan Han <yanhan@viki.com>
README - Change `Example Usage` into a section heading

Signed-off-by: Pang Yan Han <yanhan@viki.com>
README - add `TODO` section heading

Signed-off-by: Pang Yan Han <yanhan@viki.com>