Add challenge hints and ebook-links (for #305)
Add challenge hints and ebook-links
(for #305)

oviroman/disertatieiap2017,bkimminich/juice-shop,m4l1c3/juice-shop,bonze/juice-shop,oviroman/disertatieiap2017,m4l1c3/juice-shop,oviroman/disertatieiap2017,bonze/juice-shop,bkimminich/juice-shop,bkimminich/juice-shop,bonze/juice-shop,m4l1c3/juice-shop,oviroman/disertatieiap2017,bonze/juice-shop,bkimminich/juice-shop,m4l1c3/juice-shop,oviroman/disertatieiap2017,bkimminich/juice-shop,m4l1c3/juice-shop,bonze/juice-shop,bkimminich/juice-shop