Add symlinks from debian12 to debian10

Currently the installation instructions for the toolkit won't work on Debian 12 bookworm because the APT repository has no entry for debian12. The current workaround is to use the repository for Debian 11, which has been working for me for a few months now, and it seems that other users are having similar luck.

This commit adds a symlink between debian12 and debian10, in much the same way as for debian11 to debian10, and ubuntu20.04 and ubuntu22.04 to ubuntu18.04. I tided to mirror existing conventions in the stable and experimental branches.

Closes nvidia-container-toolkit#75 and libnvidia-container#211 on GitHub.

Signed-off-by: Chris Harrison dev@ravngr.com