Support updating values in empty documents

pkg/utils/yaml_utils/yaml_utils_test.go

@@ -31,6 +31,14 @@ func TestUpdateYamlValue(t *testing.T) {
 			expectedOut: "foo: bar\nfoo2: baz\n",
 			expectedErr: "",
 		},
+		{
+			name:        "add new key and value when document was empty",
+			in:          "",
+			path:        []string{"foo"},
+			value:       "bar",
+			expectedOut: "foo: bar\n",
+			expectedErr: "",
+		},
 		{
 			name:        "preserve inline comment",
 			in:          "foo: bar # my comment\n",