doc: avoid colloquialism

I witnessed an English-as-a-second-language speaker puzzle over the word "borked" in our documentation today. Reword to avoid colloquialisms. It's more precise and clear this way anyway. Also reformat Optional: to be consistent with how it appears elsewhere in the doc.

Checklist

• documentation is changed or added
• commit message follows commit guidelines

Affected core subsystem(s)

doc