I’ve only now stumbled on this document:
It’s arguably the most important resource for newcomers, and probably the second one to read after instructions on how to create a class in the UE4 editor and compile it in Visual Studio. However, I could only find it by accessing a link on the Unreal Engine API page; I had skimmed over when I initially read that page.
As I believe it would be worthwhile to link to the Getting Started with the Unreal Engine API document directly in the table of contents of the Programming Guide page, I have created this poll. As soon as more than 10 people say yes, I will mention this thread in the Feedback for Epic forum.