Add banner about the GCP credit to docs

As we deprecated the certificate-based cluster creation,
we want to add the GCP credit banner to the docs
related to IaC cluster connection method.

doc/user/infrastructure/clusters/connect/new_gke_cluster.md

@@ -6,6 +6,13 @@ info: To determine the technical writer assigned to the Stage/Group associated w
 
 # Create a Google GKE cluster
 
+INFO:
+Every new Google Cloud Platform (GCP) account receives [$300 in credit](https://console.cloud.google.com/freetrial),
+and in partnership with Google, GitLab is able to offer an additional $200 for new
+GCP accounts to get started with the GitLab integration with Google Kubernetes Engine.
+[Follow this link](https://cloud.google.com/partners/partnercredit/?pcn_code=0014M00001h35gDQAQ#contact-form)
+and apply for credit.
+
 Learn how to create a new cluster on Google Kubernetes Engine (GKE) through
 [Infrastructure as Code (IaC)](../../index.md). This process uses the Google
 and Kubernetes Terraform providers create GKE clusters. You connect the clusters to GitLab