Add information about where to download when downloading Tails in Tails

When downloading Tails in Tails (following instructions https://tails.boum.org/upgrade/tails/index.en.html), the default download folder is "Tor Browser", so the file is downloaded in the RAM. It should not work with 2GB of RAM (the system requirements). I had the problem today with 4GB of RAM, Tails finally freeze.

Maybe a warning can be added to suggest to download in the "Persistent" folder if enabled?