[llvm] [NFC][CodingStandard] Add additional example for if-else brace rule (PR #111733)

[Mehdi Amini via llvm-commits]

joker-eph wrote:

I see this example as covering what the text already states:

> readability is also harmed if an ``if``/``else`` chain does not use braced bodies for either all or none of its members

The example sections is meant to illustrate the text, so LGTM here.

https://github.com/llvm/llvm-project/pull/111733