doc: Add note about distro's `g++-mingw-w64-x86-64-posix` version

This PR stems from a requirement for the g++ minimum supported version being >= 11:

• https://packages.ubuntu.com/noble/g++-mingw-w64-x86-64-posix
• https://packages.debian.org/bookworm/g++-mingw-w64-x86-64-posix