• Add a simple example to uname(1) manual page to show how the hardware platform (returned by -m) can be different from the machine's processor architecture (-p)
• Document that make(1) sets universal MACHINE and MACHINE_ARCH variables based on these values

Reviewed by: imp, manpages (bjk)
Approved by: bjk, imp (implied)
Differential Revision: https://reviews.freebsd.org/D10489