[clang] [LifetimeSafety] Add support for iterator arithmetic (PR #195442)

[Utkarsh Saxena via cfe-commits]

https://github.com/usx95 commented:

Can you also briefly update the documentation for Pointer `LifetimePointerDocs` in file: `clang/include/clang/Basic/AttrDocs.td`

https://github.com/llvm/llvm-project/pull/195442