docs: name the AQE query stages on the operator support page

[andygrove]

Which issue does this PR close?

No issue. This is a small docs fix.

Rationale for this change

TableCacheQueryStageExec isn't on the Spark Operator Support page, so it looks like an operator Comet doesn't support yet. It's an AQE query stage, which does no data processing, and Comet already handles it: #5733 lets AQE wrap Comet's cache scan in the stage, and #6208 keeps the operators above it native after AQE re-plans them. The page's Wrapper nodes section already counts it as one of "the AQE query stages", but it names only ResultQueryStage, so searching the page for TableCacheQueryStage finds nothing.

What changes are included in this PR?

The Wrapper nodes paragraph in operators.md now names all four AQE query stages: ShuffleQueryStage, BroadcastQueryStage, TableCacheQueryStage (Spark 3.5 and later), and ResultQueryStage (Spark 4.0 and later). These are the stages that the contributor guide's "Operators That Should Not Be Converted" section lists.

How are these changes tested?

Docs only. Prettier passes on the changed file.

[sunchao]

Summary

• Prior state and problem: The operator support page referred to AQE query stages without naming TableCacheQueryStage, making its handling unclear.
• Design approach: Explicitly name all four stages in the existing wrapper paragraph.
• Correctness / compatibility analysis: Spark sources across supported 3.4–4.2 lines confirm the stage names and version boundaries. TableCacheQueryStageExec appears in 3.5 and ResultQueryStageExec in 4.0. Comet’s existing stage handling and coverage counting support the description.
• Key design decisions: Keep scheduling wrappers separate from processing operators. The clarification adds no runtime overhead or implementation complexity.
• Implementation sketch: One paragraph changes in docs/source/user-guide/latest/operators.md.
• Behavioral changes worth calling out: Documentation becomes more searchable. Comparison with branch-1.1 found no runtime behavior change attributable to this PR.
• Suggested improvements: None. No introduced P1/P2 issues found within this review.

Reviewed the entire diff from 0dec85749827fc63b30ad66a1bd074c2c313bdb2 to 3235ec97866607caecfdf2b8fc12b17dca92e747. Confirmed the PR is not a draft. Snapshot and live discussion checks contained no reviews or comments, and the snapshot contained no review threads.

Routed skills: review-comet-pr; no sibling skill applies to this documentation-only change.

Exact-head CI: check-pr-title and label passed. Preflight and Analyze Actions remain in progress. No completed failures were reported.

Validation: git diff --check passed. No builds, runtime tests, documentation rendering, or Prettier checks were run locally. CI is not yet final.