docs: improve documentation of rule

[ematipico]

Summary

Closes #3476

Test Plan

N/A

[codspeed-hq]

CodSpeed Performance Report

Merging #3999 will degrade performances by 6.36%

_{Comparing docs/improve-rule-top-level (bf7682e) with main (6922305)}

Summary

⚡ 1 improvements
❌ 1 regressions
✅ 105 untouched benchmarks

⚠️ Please fix the performance issues or acknowledge them on CodSpeed.

Benchmarks breakdown

	Benchmark	main	docs/improve-rule-top-level	Change
❌	router_17129688031671448157.ts[cached]	2.1 ms	2.2 ms	-6.36%
⚡	eucjp_1600564308684076393.json[uncached]	1,190.2 µs	964.7 µs	+23.38%