[clang-tools-extra] [clangd] Add CodePatterns config option under Completion (PR #137613)

[Nathan Ridge via cfe-commits]

HighCommander4 wrote:

@Noustaa if you'd like to also submit a documentation patch for https://clangd.llvm.org/config.html (source at https://github.com/llvm/clangd-www/blob/main/config.md), that would be appreciated!

https://github.com/llvm/llvm-project/pull/137613