Fix Underscore.js URL
Fix Underscore.js URL

Fix [old](documentcloud.github.com/underscore) dead link to the [new](underscorejs.org) one.
As seen on documentcloud.org/opensource.
WPO-Foundation/Wappalyzer,WPO-Foundation/Wappalyzer,AliasIO/wappalyzer,AliasIO/wappalyzer,WPO-Foundation/Wappalyzer