Docs: add conf remote API warning (atlassian#725)

Author: ometelytsia

docs/dc-apps-performance-toolkit-user-guide-confluence.md

@@ -152,6 +152,10 @@ After creating the development environment Confluence Data Center, generate test
 Make sure **English** language is selected as a default language on the **![cog icon](/platform/marketplace/images/cog.png) > General configuration > Languages** page. Other languages are **not supported** by the toolkit.
 {{% /warning %}}
 
+{{% warning %}}
+Make sure **Remote API** is enabled on the **![cog icon](/platform/marketplace/images/cog.png) > General configuration > Further Configuration** page.
+{{% /warning %}}
+
 1. Clone [Data Center App Performance Toolkit](https://github.com/atlassian/dc-app-performance-toolkit) locally.
 1. Follow the [README.md](https://github.com/atlassian/dc-app-performance-toolkit/blob/master/README.md) instructions to set up toolkit locally.
 1. Navigate to `dc-app-performance-toolkit/app` folder.