Mark file-based service bindings as GA (remove "experimental") (#4906)

Author: jochenehret

docs/v3/source/includes/resources/app_features/_supported_features.md.erb

@@ -6,5 +6,5 @@ Name | Description
 ---- | -----------
 **ssh** | Enable SSHing into the app
 **revisions** | Enable [versioning](#revisions) of an application
-**service-binding-k8s** | Enable k8s service bindings for the app (experimental)
-**file-based-vcap-services** | Enable file-based VCAP service bindings for the app (experimental)
+**service-binding-k8s** | Enable k8s service bindings for the app
+**file-based-vcap-services** | Enable file-based VCAP service bindings for the app