Review docs for undefined acronyms and expand them on first use #9

Goal

Make Core docs easier to read for contributors outside the immediate project context.

Suggested scope

• Review top-level docs for acronyms that may not be obvious.
• Expand acronyms on first use where helpful.
• Avoid rewriting technical content beyond clarity fixes.

Acceptance criteria

• At least 5 unclear acronyms or shorthand terms are reviewed.
• Any expansions are consistent with existing usage.
• The PR stays focused on readability.

Contributor note

This is a low-risk docs cleanup task.