Along with iOS 11 came a feature that lets you scan documents and save them as PDF files. This is how you do it:
Open the Notes app.
Create a new note by tapping the icon in the top right corner.
Tap the circled plus sign above the keyboard and choose Scan Documents.
Hold your iPad camera above the first document until you hear a camera click. Repeat for the rest of the documents.
Tap Save in the bottom right corner to return to the scanned documents.
Tap the share button above and to the right of the document, then choose Create PDF on the bottom row of icons.
This will open the PDF in preview mode. To send it somewhere else, tap the share button to the right above the PDF.
Hopefully Apple will add an OCR feature in the future.