Update README.md

Added GTM data layer resources

Author: krizel4

README.md

@@ -8,9 +8,12 @@ In the word document, the block name is "marketoform" and in the text content ar
 - [Munchkin ID](https://nation.marketo.com/t5/knowledgebase/how-to-find-your-munchkin-id-for-a-marketo-instance/ta-p/248432)
 - Form Id: In the photo example below, you can see the 4-digit form ID after the Munchkin ID (162-LBR-557).
 ![Example of embed form code from Marketo](https://experienceleague.adobe.com/en/docs/marketo/using/product-docs/demand-generation/forms/form-actions/media_143d0c35a972b429e2ddb7dda1cda3cf22866e8ee.png)
-- dataLayer.push for Google Tag Manager [Link to Add'l Info from Marketo Engage Community](https://nation.marketo.com/t5/product-discussions/how-to-track-marketo-forms-in-google-analytics-using-using-api/td-p/305735)
-    - event: 'marketo.success'
+- Google Tag Manager Data Layer
     - 'marketo.timestamp': new Date().toLocaleTimeString()
     - 'marketo.form_id': formId
     - 'marketo.form_values': values
     - 'marketo.follow_up_url': followUpUrl
+
+## Additional Resources for GTM dataLayer
+- [Analytics Mania: Enrich Form Submission Data with GTM](https://www.analyticsmania.com/post/enrich-form-submission-data-with-google-tag-manager/)
+- [Marketo Specific Resource for GTM Data Layer](https://nation.marketo.com/t5/product-discussions/how-to-track-marketo-forms-in-google-analytics-using-using-api/td-p/305735)