Missing documentation on Get Currently Playing Track response codes

[mcgurk]

I'm the maintainer of spotify-web-api-php and recently got a bug regarding the Get Currently Playing Track endpoint returning an empty body when nothing is playing at all and no device is active. However, the docs doesn't reflect this.

While digging into it I noticed that the Get Playback State endpoint behaves in the same way but here the documentation is correct.

Could the documentation be updated to include that response possibility too? Thanks!