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

[Konrad Kleine via llvm-commits]

kwk wrote:

> It seems like the docs use a mix of both styles -- should we normalize to one or the other for _all_ options?

Oh, indeed. I must say in terms of readability I like the one without the `=` better.

Here are some stats:

* There are 53 options in the file
  * `grep '.. option::' llvm/docs/CommandGuide/lit.rst | wc -l`
* There are 22 options with additional arguments (e.g. in capital letters)
  * `grep '.. option::' llvm/docs/CommandGuide/lit.rst | grep -P '[A-Z=]' | wc -l`
* Out of the 22 options with arguments, there are 14 options that use "=" and 7 that use no "=".
  * grep '.. option::' llvm/docs/CommandGuide/lit.rst | grep -P '[A-Z]' | grep "=" | wc -l`
  * grep '.. option::' llvm/docs/CommandGuide/lit.rst | grep -P '[A-Z]' | grep -v "=" | wc -l`

That means the majority of options with additional arguments uses "=".

Consistency wise we should probably use "=" for this PR and the rest as well. I've changed this PR accordingly. 

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