Tweaks after proofreading the 2.6 OptionsResolver stuff

Hi guys!

This is a proofread after merging #4159. There were enough changes there that the easiest way to handle things was to merge, re-read entirely, then open a PR with small tweaks. But largely, I am very happy with how the document turned out :).

| Q             | A
| ------------- | ---
| Doc fix?      | yes
| New docs?     | no
| Applies to    | 2.6+
| Fixed tickets | --

Thanks!
I thought about this - but I don't think it's necessary, since even the 2.7 or 2.8 CHANGELOG will contain the 2.6 section. So I think we're ok :) That being said, if we remember to change it later, I think that's just fine.