The External Link tool is a simple tool that redirects to the configured URL. This is often used to provide a navigation bar item that points to external code repositories, forums, or donation systems.
The External Link tool is installed via Admin -> Tools, just like any other tool.
The Label will determine how the link is displayed in the navigation bar.
The Mount Point will determine the URL of the link before it redirects. The destination URL is configured afterwards.
Once the External Link tool is installed, select Options to configure the destination URL.