docs: Add GPU support highlight

Add an item about GPU support for AI linking to relevant tutorials.

Author: nirs

site/content/en/docs/_index.md

@@ -16,6 +16,7 @@ minikube quickly sets up a local Kubernetes cluster on macOS, Linux, and Windows
 ## Highlights
 
 * Supports the latest Kubernetes release (+6 previous minor versions)
+* Supports GPUs for AI developement ([nvidia]({{< ref "/docs/tutorials/nvidia.md" >}}), [amd]({{< ref "/docs/tutorials/amd.md" >}}), [apple]({{< ref "/docs/tutorials/ai-playground.md" >}}))
 * Cross-platform (Linux, macOS, Windows)
 * Deploy as a VM, a container, or on bare-metal
 * Multiple container runtimes (CRI-O, containerd, docker)