Reference for RPM spec macros (%setup, %buildroot, etc)

Solution 1:

The Fedora Project hosts the best documentation on RPM out there in html format:

See also:

Prior to these resources, my go to guide was Maximum RPM (which you also found):

Solution 2:

Some of them are documented in Maximum RPM, Taking the RPM Package Manager to the Limit by Edward C. Bailey.

Section Macros: Helpful Shorthand for Package Builders describes %setup and %patch macros.