[llvm] Add security group 2023 transparency report. (PR #80320)

[Peter Smith via llvm-commits]

smithp35 wrote:

This is the same as https://github.com/llvm/llvm-project/pull/80272 but with a typo fixed. I managed to mess up my branch when I had problems pushing the fixup. I've created a new pull request to make sure I don't introduce any problems upstream.
 

https://github.com/llvm/llvm-project/pull/80320