docs(kubernetes): add more fleshed-out example of a Demo Kubernetes cluster (#2329)

This Kubernetes cluster has:

- vLLM for serving an inference model
- vLLM for serving a safety model
- Postgres DB (for metadata and other state for the Llama Stack distro)
- Chroma DB for Vector IO (memory)

Perhaps most importantly, this was me trying to learn Kubernetes for the
first time.

## Test Plan

Run `sh apply.sh` against an EKS cluster, then after `kubectl
port-forward service/llama-stack-service 8321:8321` and after many
attempts, we have finally:

<img width="1589" alt="image"
src="https://github.com/user-attachments/assets/c69f242d-6aaa-4def-9f7c-172113b8bfc1"
/>

<img width="1978" alt="image"
src="https://github.com/user-attachments/assets/cf678404-f551-4fa5-9077-bebe3e8e8ae8"
/>

docs/source/distributions/k8s/chroma-k8s.yaml.template

@@ -0,0 +1,66 @@
+apiVersion: v1
+kind: PersistentVolumeClaim
+metadata:
+  name: chromadb-pvc
+spec:
+  accessModes:
+    - ReadWriteOnce
+  resources:
+    requests:
+      storage: 20Gi
+---
+apiVersion: apps/v1
+kind: Deployment
+metadata:
+  name: chromadb
+spec:
+  replicas: 1
+  selector:
+    matchLabels:
+      app: chromadb
+  template:
+    metadata:
+      labels:
+        app: chromadb
+    spec:
+      containers:
+      - name: chromadb
+        image: chromadb/chroma:latest
+        ports:
+        - containerPort: 6000
+        env:
+        - name: CHROMA_HOST
+          value: "0.0.0.0"
+        - name: CHROMA_PORT
+          value: "6000"
+        - name: PERSIST_DIRECTORY
+          value: "/chroma/chroma"
+        - name: CHROMA_DB_IMPL
+          value: "duckdb+parquet"
+        resources:
+          requests:
+            memory: "512Mi"
+            cpu: "250m"
+          limits:
+            memory: "2Gi"
+            cpu: "1000m"
+        volumeMounts:
+        - name: chromadb-storage
+          mountPath: /chroma/chroma
+      volumes:
+      - name: chromadb-storage
+        persistentVolumeClaim:
+          claimName: chromadb-pvc
+---
+apiVersion: v1
+kind: Service
+metadata:
+  name: chromadb
+spec:
+  selector:
+    app: chromadb
+  ports:
+  - protocol: TCP
+    port: 6000
+    targetPort: 6000
+  type: ClusterIP