add /api legacy routes

src/Jackett/Startup.cs

@@ -191,6 +191,16 @@ namespace Jackett
                 }
             );
 
+            config.Routes.MapHttpRoute(
+                name: "LegacyTorznab",
+                routeTemplate: "torznab/{indexerId}/api",
+                defaults: new
+                {
+                    controller = "Results",
+                    action = "Torznab"
+                }
+            );
+
             // Legacy fallback for Potato results
             config.Routes.MapHttpRoute(
                 name: "LegacyPotato",
@@ -202,6 +212,16 @@ namespace Jackett
                 }
             );
 
+            config.Routes.MapHttpRoute(
+                name: "LegacyPotato",
+                routeTemplate: "potato/{indexerId}/api",
+                defaults: new
+                {
+                    controller = "Results",
+                    action = "Potato"
+                }
+            );
+
             config.Routes.MapHttpRoute(
                 name: "WebUI",
                 routeTemplate: "UI/{action}",