[llvm] Add release note for parallel module creation in LLDB (PR #116857)

[David Spickett via llvm-commits]

DavidSpickett wrote:

Assuming I remember, I will trawl the git log prior to the 20 branch and see if there's anything release note worthy.

But in the meantime glad to see more being added.

https://github.com/llvm/llvm-project/pull/116857