feat(vertexai): update README with more details and links (googleapis…

…#9146)

vertexai/README.md

@@ -1,13 +1,47 @@
 # Vertex AI Go SDK
 
->[!IMPORTANT]
->Thanks for your interest in the Vertex AI SDKs! **You can start using this SDK
->and its samples on December 13, 2023.** Until then, check out our [blog
->post](https://blog.google/technology/ai/google-gemini-ai/) to learn more about
->Google's Gemini multimodal model.
+[![Go Reference](https://pkg.go.dev/badge/cloud.google.com/go/vertexai.svg)](https://pkg.go.dev/cloud.google.com/go/vertexai)
+
+The Vertex AI Go SDK enables developers to use Google's state-of-the-art 
+enerative AI models (like Gemini) to build AI-powered features and applications.
+This SDK supports use cases like:
+- Generate text from text-only input
+- Generate text from text-and-images input (multimodal)
+- Build multi-turn conversations (chat)
+
+For example, with just a few lines of code, you can access Gemini's multimodal
+capabilities to generate text from text-and-image input.
+
+```go
+model := client.GenerativeModel("gemini-pro-vision")
+img := genai.ImageData("jpeg", image_bytes)
+prompt := genai.Text("Please give me a recipe for this:")
+resp, err := model.GenerateContent(ctx, img, prompt)
+```
+
+## Installation and usage
+
+Add the SDK to your module with `go get cloud.google.com/go/vertexai/genai`.
+
+For detailed instructions, you can find a [quickstart](http://cloud.google.com/vertex-ai/docs/generative-ai/start/quickstarts/quickstart-multimodal)
+for the Vertex AI Go SDK in the Google Cloud documentation.
+
+## Documentation
+
+You can find complete documentation for the Vertex AI SDKs and the Gemini
+model in the Google Cloud documentation: https://cloud.google.com/vertex-ai/docs/generative-ai/learn/overview
+
+You can also find information about this SDK in the
+[Go package documentation](https://pkg.go.dev/cloud.google.com/go/vertexai).
+
+## Contributing
+
+See [Contributing](https://github.com/googleapis/google-cloud-go/blob/main/CONTRIBUTING.md)
+for more information on contributing to the Vertex AI Go SDK.
+
+## License
+
+The contents of this repository are licensed under the
+Apache License, version 2.0](http://www.apache.org/licenses/LICENSE-2.0).
 
-The Vertex AI Go SDK enables developers to use Google's state-of-the-art
-generative AI models (like Gemini) to build AI-powered features and
-applications.
 
-*More details and information coming soon!*