Update query-metadata-style-guide.md

[jonjanego]

clarifying usage of top level tags

[Copilot]

Pull Request Overview

Clarifies the use of top-level @tags for code quality queries and introduces sub-categories for finer grouping.

• Adds instruction to assign exactly one top-level tag (maintainability or reliability)
• Removes outdated bullets and updates phrasing around sub-categories
• Begins listing sub-categories (currently for maintainability)

Comments suppressed due to low confidence (2)

docs/query-metadata-style-guide.md:161

• This bullet duplicates the top-level maintainability tag under sub-categories. Consider replacing it with actual sub-categories (e.g., readability, complexity) rather than repeating the top-level tag.

* `@tags maintainability`–for queries that detect patterns that make it harder for developers to make changes to the code.

docs/query-metadata-style-guide.md:159

• [nitpick] Sub-categories are shown only for maintainability; consider adding parallel sub-categories for reliability to maintain consistency.

In addition to the "top-level" categories, we will also add sub-categories to further group code quality related queries: