The README's compiler list still named GCC 14.2, Clang 21.0, Apple
Clang 16.0, Intel C++ 17.0.2, nvcc 11.0.221, and MSVC up to 2022,
which no longer matches the CI matrix. List what the workflows test
now, with versions taken from the compiler identification in the CI
logs of the latest develop runs: GCC 4.8 - 16.2, Clang 3.4 - 22.1,
Apple Clang 15.0 - 21.0 (Xcode 15.0.1 up to macos-latest), icpc
2021.10, icpx 2025.3, nvcc 11.8 - 12.6, nvc++ 25.5, and MSVC 2015 -
2026. Apple Clang now starts at 15.0 because CI no longer runs older
Xcode versions; icpc 2021.10 is the last release of that compiler.
CITATION.cff pointed repository-code at the user profile instead of
the repository.
Documentation and metadata only; the library is unchanged.
Part of #5716
Signed-off-by: Niels Lohmann <mail@nlohmann.me>