Just click on the image to see the full article. As they note in thier post, if you have iCloud syncing turned on, this will add that pdf to iBooks on all your devices.
The steps are...
... lauch safari
... navigate to a pdf
... tap on the screen of the ipad to reveal the overlay menu
... tap open in iBooks button
... iBooks will launch and add that pdf to your collection
again... here is the link to see the imore post complete with scre