Add examples of the 3rd-party Python-like, but C++ `fmt` library

[ElectricRCAircraftGuy]

https://github.com/fmtlib/fmt

My notes from my Chrome bookmark to it:

fmtlib/fmt: A modern formatting library [modern C++ string formatting library alternative to printf(), fprintf(), iostream, etc.; made by Victor Zverovich (https://github.com/vitaut), also the author of C++20's std::format. #include <fmt/core.h>, fmt::print(); ex: std::cout << fmt::format(FMT_STRING("hello {}; var = {}"), "world", var);]