Add example config for docs, and add to docs test

assets/docs/configuration/transformations/snowplow-builtin/spGtmssPreview-full-example .hcl

@@ -0,0 +1,4 @@
+transform {
+  use "spGtmssPreview" {
+  }
+}

assets/docs/configuration/transformations/snowplow-builtin/spGtmssPreview-minimal-example.hcl

@@ -0,0 +1,4 @@
+transform {
+  use "spGtmssPreview" {
+  }
+}

docs/configuration_transformations_docs_test.go

@@ -160,6 +160,8 @@ func testTransformationConfig(t *testing.T, filepath string, fullExample bool) {
 			configObject = &transform.Base64DecodeConfig{}
 		case "base64Encode":
 			configObject = &transform.Base64EncodeConfig{}
+		case "spGtmssPreview":
+			configObject = &transform.GTMSSPreviewConfig{}
 		case "js":
 			configObject = &engine.JSEngineConfig{}
 		case "lua":

pkg/transform/snowplow_gtmss_preview.go

@@ -9,6 +9,10 @@ import (
 	"github.com/snowplow/snowplow-golang-analytics-sdk/analytics"
 )
 
+// GTMSSPreviewConfig is a configuration object for the spEnrichedToJson transformation
+type GTMSSPreviewConfig struct {
+}
+
 // The gtmssPreviewAdapter implements the Pluggable interface
 type gtmssPreviewAdapter func(i interface{}) (interface{}, error)