[clang-tools-extra] [clang-tidy] [docs] Replace _not_ in reserved-identifier.rst with *not* (PR #112162)

[Nick Riasanovsky via cfe-commits]

njriasan wrote:

@carlosgalvezp I think the force push fixed it. Could you confirm that you no longer see the second author? Thanks.

https://github.com/llvm/llvm-project/pull/112162