[llvm] [docs] use "=" in options with arguments (PR #142340)

[Konrad Kleine via llvm-commits]

kwk wrote:

> The print test that `lit` itself prints uses whitespace instead of `=`, so I'd be inclined to normalize the other way around...

Like I said, this would have been my favourable way too but I went with the majority of what was in the file. Let me work on this real quick.

https://github.com/llvm/llvm-project/pull/142340