Fix the example for Place.details

[vasco3]

the example is shown as an async/await but it is missing the keywords.
I rewrote it with a promise, so it matches the Places Autocomplete example

[mcabs3]

Thanks for taking the time to look at this project. I always appreciate the help maintaining it. I am currently working (and almost finishing) a v2 which will use a different syntax/pattern so these docs will be obsolete.

I actually prefer using the async/await form in my readme so its easier for people to see, but yes I am making an assumption that their code is in an environment that supports it (and in an async function).

If you would like to update the autocomplete example to use async/await that would be a big help.

[vasco3]

no problem, updated.