Fix comment about heartbeat interval timeout

src/uas/UASInterface.h

@@ -646,7 +646,7 @@ signals:
 protected:
 
     // TIMEOUT CONSTANTS
-    static const unsigned int timeoutIntervalHeartbeat = 3500 * 1000; ///< Heartbeat timeout is 2.5 seconds
+    static const unsigned int timeoutIntervalHeartbeat = 3500 * 1000; ///< Heartbeat timeout is 3.5 seconds
 
 };