RFC Reader is a professional tool for reading RFC document. It can generate a section directory tree. And it provides lots of features to help you reading RFC documents, such as bookmark, highlight, search, and automatically record where you are reading. Version 3.2 is optimized and it is free now! You can use it without any limitation.
There's a feature built into iOS 11, iOS 12, and iPadOS that is one of those love/hate features -- you'll either love it because it will dramatically improve your typing speed, or you'll hate it because it.