docs: "Symbols of scaled units" chapter added + minor updates to scal… #234

Job	Run time
std::format none C++20 Clang-18 Release	7m 38s
std::format none C++20 Clang-18 Debug	5m 43s
std::format none C++23 Clang-18 Release	5m 53s
std::format none C++23 Clang-18 Debug	6m 32s
std::format gsl-lite C++20 Clang-18 Release	7m 27s
std::format gsl-lite C++20 Clang-18 Debug	6m 51s
std::format gsl-lite C++23 Clang-18 Release	7m 6s
std::format gsl-lite C++23 Clang-18 Debug	6m 50s
std::format ms-gsl C++20 Clang-18 Release	7m 18s
std::format ms-gsl C++20 Clang-18 Debug	7m 7s
std::format ms-gsl C++23 Clang-18 Release	6m 17s
std::format ms-gsl C++23 Clang-18 Debug	6m 47s
fmtlib none C++20 Clang-18 Release	7m 26s
fmtlib none C++20 Clang-18 Debug	7m 0s
fmtlib none C++23 Clang-18 Release	7m 0s
fmtlib none C++23 Clang-18 Debug	6m 48s
fmtlib gsl-lite C++20 Clang-18 Release	7m 29s
fmtlib gsl-lite C++20 Clang-18 Debug	7m 4s
fmtlib gsl-lite C++23 Clang-18 Release	7m 16s
fmtlib gsl-lite C++23 Clang-18 Debug	6m 58s
fmtlib ms-gsl C++20 Clang-18 Release	7m 55s
fmtlib ms-gsl C++20 Clang-18 Debug	7m 5s
fmtlib ms-gsl C++23 Clang-18 Release	7m 9s
fmtlib ms-gsl C++23 Clang-18 Debug	7m 0s
	2h 47m 39s

Provide feedback