Documentation for expected usage of rpm.deps file

System dependencies for debian systems can be easily read from (and installed) using the provided `deb.deps` file. There was even documentation added showing an example of this in #165. This is great!

Alongside this `dep.deps` file is an `rpm.deps` file, presumably to be used on rpm based systems. The problem however is that usage of this file is not as clear cut, since its contents cannot be (from my understanding) read directly and "just installed". Rather, it's up to the user to decide what is applicable to their system, where to source certain shared libraries, etc, alongside some more typical packages that can be "just installed".

This is workable, but to folks like myself without much experience on rpm based systems, my current 90% automated, 10% manual process of sourcing and downloading required system dependencies based on `rpm.deps` leaves me wondering if I'm doing it right. (I feel like I'm misunderstanding something...)

Just as #165 eludes to in a [comment on that PR](https://github.com/GoogleChromeLabs/chrome-for-testing/pull/165#issuecomment-2596065343), **I believe there should be documentation about the expected usage of `rpm.deps`, as its not clear to me what that is.** Even if this file is only meant to be reference and not actually used programmatically, I think stating that would clear some confusion.