Please improve the documentation, it can mislead users:
1) we must not fill "Log time format" from, it's an optional parameter (https://www.zabbix.com/documentation/2.4/manual/config/items/itemtypes/log_items#configuration). I propose to change "Specifically for log monitoring items you must enter:" phrase or move information about "Log time format" in a different place on this page.
2) please improve the tip on "Aggregate checks" page (https://www.zabbix.com/documentation/2.4/manual/config/items/itemtypes/aggregate). How about to use "Only active, existing items on enabled hosts are included in the calculations." instead of "Only active items on enabled hosts are included in the calculations."?
3) The "CPU" recommendation from "Examples of hardware configuration" is very old. How about to use the next values:
Name ... CPU/Memory ...
Small ... 1 CPU Core/256MB ...
Medium ... 2 CPU Cores/2GB ...
Large ... 4 CPU Cores/8MB ...
Very large ... 8 CPU Cores/16GB ...