[AIG]Improve Google Vertex AI docs (#19256)

* Improve Google Vertex AI docs

* Update vertex.mdx

money edit.

Author: daisyfaithauma

src/content/docs/ai-gateway/providers/vertex.mdx

@@ -8,6 +8,18 @@ sidebar:
 
 [Google Vertex AI](https://cloud.google.com/vertex-ai) enables developers to easily build and deploy enterprise ready generative AI experiences.
 
+Below is a quick guide on how to set your Google Cloud Account:
+
+1. Google Cloud Platform (GCP) Account
+
+   - Sign up for a [GCP account](https://cloud.google.com/vertex-ai). New users may be eligible for credits (valid for 90 days).
+
+2. Enable the Vertex AI API
+
+   - Navigate to [Enable Vertex AI API](https://console.cloud.google.com/marketplace/product/google/aiplatform.googleapis.com) and activate the API for your project.
+
+3. Apply for access to desired models.
+
 ## Endpoint
 
 ```txt