Clarify Boolean collection code generation

[connortsui20]

Summary

Clarifies the callback contract and code-generation behavior of BitBuffer::collect_bool, including the remaining AVX-512 mask-to-bytes-to-mask conversion tracked by LLVM #219235.

Changes

Documents when to use the inlined and runtime-multiversioned collectors, and replaces the duplicate BitBufferMut explanations with links to the canonical BitBuffer documentation.

[codspeed-hq]

Merging this PR will improve performance by 20.46%

⚠️ Unknown Walltime execution environment detected

Using the Walltime instrument on standard Hosted Runners will lead to inconsistent data.

For the most accurate results, we recommend using CodSpeed Macro Runners: bare-metal machines fine-tuned for performance measurement consistency.

⚡ 1 improved benchmark
✅ 2138 untouched benchmarks
⏩ 106 skipped benchmarks¹
🗄️ 4 archived benchmarks run²

Performance Changes

	Mode	Benchmark	BASE	HEAD	Efficiency
⚡	WallTime	arrow_checked_add_u32_avx2[16384]	21.3 µs	17.7 µs	+20.46%

Tip

Curious why performance improved? Comment @codspeedbot explain why performance improved on this PR, or directly use the CodSpeed MCP with your agent.

---

_{Comparing ct/collect-bool-docs (81fa252) with develop (f880575)}

Footnotes

1. 106 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩

2. 4 benchmarks were run, but are now archived. If they were deleted in another branch, consider rebasing to remove them from the report. Instead if they were added back, click here to restore them. ↩