The manual is simply outdated. But the good news is that we have tutorials here on the forum under the FAQ section. In particular these could be of interest to you:
- Tutorial: How to make a footprint in KiCad 5.1.x (From scratch)?
- Creating a new footprint library
- Library management in KiCad version 5
The footprint editor in v5.1 works the same way as the symbol editor. So this will also help (is linked from the create a new footprint library entry, added here for convinience) Creating a new symbol library and a new symbol in KiCad 5