docs: simplify rules benchmark headers

[kvlonge]

Why

Evaluation counts made the Rules benchmark headers wider and harder to scan. Readers primarily need the compile scenarios, Rule counts, and timings.

Changes

• remove evaluation counts from the benchmark table headers
• retain approximate evaluation scale in explanatory text below the table
• simplify the Rules overview performance summary
• preserve all measured timings and exact cache-invalidation results

Verification

• validated docs.json
• git diff --check
• public-repository hygiene scan
• reviewed the rendered three-column table structure