One of the more subtle new features in iOS 9 is that you can now leverage Apple’s built-in iBooks app to save documents and web pages into PDF files. To access this, bring up the normal iOS 9 Share Sheet — the same one you would use to share something to Twitter or Facebook — and scroll over to the right side of the list and a “Save PDF to iBooks” option should appear. Selecting the option will open iBooks and the document or…