Release notes: map sector compression (#8485)

Collecting practical notes so new server owners avoid the same traps. Environment: Ubuntu 22.04, 4 vCPU, 8GB RAM, MariaDB 10.11. We logged query times over 200ms on market browse during peak hour. Would you accept this as a draft tutorial under Learn Track?

We documented a similar path in our ops notes last month.

Map looks promising. Hunting loop needs clearer signage near the temple.

Thanks — we saw the same spike when market history grew past 500k rows.