Make `cloze` field a little more obvious?

[badlydrawnrob]

It's obvious in the documentation which field is a cloze, but not so much in the editor.

{{cloze:★ Key point (code block or image)}} could be made more obvious as to which field is a cloze in the editor. It might also be worthwhile adding an optional cloze to some other fields too?

See below for the errors you get if you don't add a cloze tag in your card

• [ ] #40

[badlydrawnrob]