docs: concepts and building_applications migration (#3534)

# What does this PR do?

- Migrates the remaining documentation sections to the new documentation format

<!-- Provide a short summary of what this PR does and why. Link to relevant issues if applicable. -->

<!-- If resolving an issue, uncomment and update the line below -->

<!-- Closes #[issue-number] -->

## Test Plan

- Partial migration

<!-- Describe the tests you ran to verify your changes with result summaries. *Provide clear instructions so the plan can be easily re-executed.* -->

docs/docs/distributions/k8s/ui-k8s.yaml.template

@@ -0,0 +1,68 @@
+apiVersion: apps/v1
+kind: Deployment
+metadata:
+  name: llama-stack-ui
+  labels:
+    app.kubernetes.io/name: llama-stack
+    app.kubernetes.io/component: ui
+spec:
+  replicas: 1
+  selector:
+    matchLabels:
+      app.kubernetes.io/name: llama-stack
+      app.kubernetes.io/component: ui
+  template:
+    metadata:
+      labels:
+        app.kubernetes.io/name: llama-stack
+        app.kubernetes.io/component: ui
+    spec:
+      containers:
+      - name: llama-stack-ui
+        image: node:18-alpine
+        command: ["/bin/sh"]
+        env:
+        - name: LLAMA_STACK_BACKEND_URL
+          value: "http://llama-stack-service:8321"
+        - name: LLAMA_STACK_UI_PORT
+          value: "8322"
+        - name: GITHUB_CLIENT_ID
+          value: "${GITHUB_CLIENT_ID}"
+        - name: GITHUB_CLIENT_SECRET
+          value: "${GITHUB_CLIENT_SECRET}"
+        - name: NEXTAUTH_URL
+          value: "${LLAMA_STACK_UI_URL}:8322"
+        args:
+          - -c
+          - |
+            # Install git (not included in alpine by default)
+            apk add --no-cache git
+
+            # Clone the repository
+            echo "Cloning repository..."
+            git clone https://github.com/meta-llama/llama-stack.git /app
+
+            # Navigate to the UI directory
+            echo "Navigating to UI directory..."
+            cd /app/llama_stack/ui
+
+            # Check if package.json exists
+            if [ ! -f "package.json" ]; then
+              echo "ERROR: package.json not found in $(pwd)"
+              ls -la
+              exit 1
+            fi
+
+            # Install dependencies with verbose output
+            echo "Installing dependencies..."
+            npm install --verbose
+
+            # Verify next is installed
+            echo "Checking if next is installed..."
+            npx next --version || echo "Next.js not found, checking node_modules..."
+            ls -la node_modules/.bin/ | grep next || echo "No next binary found"
+
+            npm run dev
+        ports:
+        - containerPort: 8322
+        workingDir: /app