Fix typo in "Generic Option Parameter" for migration guide 0.17

[citrusmunch]

Objective

Fix migration guide code typo.

Solution

rs should be results to match the binding.

Testing

none.

[github-actions]

Your PR caused a change in the graphical output of an example or rendering test. This might be intentional, but it could also mean that something broke!
You can review it at https://pixel-eagle.com/project/B04F67C0-C054-4A6F-92EC-F599FEC2FD1D?filter=PR-22458

If it's expected, please add the M-Deliberate-Rendering-Change label.

If this change seems unrelated to your PR, you can consider updating your PR to target the latest main branch, either by rebasing or merging main into it.

[kfc35]

@citrusmunch I believe the place to open this pull request is actually the https://github.com/bevyengine/bevy-website repo
The file you want to edit is here: https://github.com/bevyengine/bevy-website/blob/main/content/learn/migration-guides/0.16-to-0.17.md

[citrusmunch]

I see! I did struggle to find the best place to send a fix, but this makes much more sense thank you.

Closing this in favor of: bevyengine/bevy-website#2344