Allow for more than one highlight

[momuno]

Is your feature request related to a problem? Please describe. When I use //@highlight more than once in a markdown block, only the last //@highlight works.

Describe the solution you'd like I would like to be able to highlight more than one item in a block hint.

Additional context

# Make a Puzzle

## Step 4

🤷 Nothing to lose 🤷

```blocks
//@highlight
let myNumber1 = 1

//@highlight
let myNumber2 = 2

//@highlight
let myNumber3 = 3