Slightly misleading mention of "asynchronous functions"

[oliverjam]

It's not possible to wrap an asynchronous function in a try/catch block, so throwing should only be used with synchronous code.

— docs/approach_2.md

This line is kind of misleading in that try/catch is exactly how you error handle a proper async function.

I know we don't teach promises/async functions before this, but given async/await are really well supported now we're going to have students who have encountered them before this week.

Not sure I have a suggestion other than to disambiguate by saying "asynchronous code" instead of "asynchronous function"