Updating WriteYAML to not add delimiter to start files

pkg/crd/testdata/gen/bar.example.com_foos.v1beta1.yaml

@@ -1,5 +1,3 @@
-
----
 apiVersion: apiextensions.k8s.io/v1beta1
 kind: CustomResourceDefinition
 metadata:

pkg/crd/testdata/gen/bar.example.com_foos.yaml

@@ -1,5 +1,3 @@
-
----
 apiVersion: apiextensions.k8s.io/v1
 kind: CustomResourceDefinition
 metadata:

pkg/genall/genall.go

@@ -130,12 +130,16 @@ func (g GenerationContext) WriteYAML(itemPath string, objs ...interface{}) error
 	}
 	defer out.Close()
 
-	for _, obj := range objs {
+	for i, obj := range objs {
 		yamlContent, err := yaml.Marshal(obj)
 		if err != nil {
 			return err
 		}
-		n, err := out.Write(append([]byte("\n---\n"), yamlContent...))
+		delimiter := ""
+		if i > 0 {
+			delimiter = "\n---\n"
+		}
+		n, err := out.Write(append([]byte(delimiter), yamlContent...))
 		if err != nil {
 			return err
 		}