Add docs for StatsRewriteRule

[AdamGS]

Summary

Adds docs for StatsRewriteRule and its functions.

Can be considered a follow-up for #8345, but can be individually merged.

[codspeed-hq]

Merging this PR will not alter performance

⚠️ 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.

⚡ 3 improved benchmarks
❌ 3 regressed benchmarks
✅ 1526 untouched benchmarks

Warning

Please fix the performance issues or acknowledge them on CodSpeed.

Performance Changes

	Mode	Benchmark	BASE	HEAD	Efficiency
❌	Simulation	chunked_bool_canonical_into[(1000, 10)]	20.5 µs	35.6 µs	-42.45%
❌	Simulation	chunked_varbinview_canonical_into[(1000, 10)]	162 µs	198.2 µs	-18.25%
❌	Simulation	chunked_varbinview_into_canonical[(1000, 10)]	177 µs	213.1 µs	-16.95%
⚡	Simulation	bitwise_not_vortex_buffer_mut[128]	273.6 ns	215.3 ns	+27.1%
⚡	Simulation	bitwise_not_vortex_buffer_mut[1024]	333.9 ns	275.6 ns	+21.17%
⚡	Simulation	bitwise_not_vortex_buffer_mut[2048]	456.9 ns	398.6 ns	+14.63%

Tip

Investigate this regression by commenting @codspeedbot fix this regression on this PR, or directly use the CodSpeed MCP with your agent.

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_{Comparing adamg/stats-rewrite-docs (3d7d303) with develop (b94291b)}