ZBXNEXT-799 implemented support for SRV record monitoring.

comment there says :
Unix part merged into pre-1.8.6.
Windows part merged into pre-1.9.5

http://www.zabbix.com/documentation/2.0/manual/config/items/itemtypes/zabbix_agent only mentions that net.dns.record is supported since 1.8.6, but supposedly should say that it's supported on windows since 2.0
it also doesn't mention the version compatibility for net.dns

http://www.zabbix.com/documentation/1.8/manual/config/items seems to be correct, as it only claims linux support for this key since 1.8.6

the documentation changes should be verified by what the code does.