Add granule download instruction to FAQ

[werzum]

Hello,
I was just using the s2 portal and trying to download a specific granule. The instructions in the FAQ/code samples only help you with downloading a given image via console and curl, but since I needed the entire folder structure I had to use wget.
Maybe you can add this to the FAQ code samples to help other with the same issue:

wget --recursive --user=user --password=password https://s2.boku.eodc.eu/granule/granule_ID