Added additional and correct list-style css code hints

See MDN for details:

https://developer.mozilla.org/en-US/docs/Web/CSS/list-style
https://developer.mozilla.org/en-US/docs/Web/CSS/list-style-type
https://developer.mozilla.org/en-US/docs/Web/CSS/list-style-image
https://developer.mozilla.org/en-US/docs/Web/CSS/list-style-position