Update Admin Area in word list

What does this MR do and why?

While working on !147144 (merged) and !147160 (merged), I noticed Administrator area and Administration area are sometimes used to refer to Admin Area. This MR updates the word list to advice against the use of these variants.

MR acceptance checklist

Please evaluate this MR against the MR acceptance checklist. It helps you analyze changes to reduce risks in quality, performance, reliability, security, and maintainability.

Screenshots or screen recordings

Screenshots are required for UI changes, and strongly recommended for all other merge requests.

Before	After

How to set up and validate locally

Numbered steps to set up and validate the change are strongly suggested.