The following article will cover the steps to enable the cfggameplay.json file on your DayZ Server Hosted By Host Havoc.
1. Log into your game panel.
2. Stop your service if it is running.
3. Click on in your game panel and then click on for the serverDZ_By_HostHavoc.cfg file.
4. Locate enableCfgGameplayFile = 0;
and change the 0 to 1 and click on
NOTE: If this line does not exist, please add it anywhere in the config file like this: enableCfgGameplayFile = 1;
For additional info on using the cfggameplay.json file, please view the official wiki.