docs(examples): add security headers to Angular example (#6947)

Author: jnomeisky

examples/angular-dashboard-with-material-ui/dashboard-app/.netlify/state.json

@@ -0,0 +1,17 @@
+{
+  "headers": [
+    {
+      "source": "/(.*)",
+      "headers": [
+        {
+          "key": "Strict-Transport-Security",
+          "value": "max-age=31536000; includeSubDomains;"
+        },
+        {
+          "key": "Content-Security-Policy",
+          "value": "default-src 'self'; script-src 'report-sample' 'self' https://www.datadoghq-browser-agent.com/datadog-logs-v4.js 'sha256-NNRNlUvekpg7yDPcWeHFgr2SbeZBup4y3/n9L6w472A='; style-src 'report-sample' 'self' https://fonts.googleapis.com 'unsafe-inline'; object-src 'none'; base-uri 'self'; connect-src 'self' https://flaky-sheep.gcp-us-central1.cubecloudapp.dev https://graphql.contentful.com https://track.cube.dev https://identity.cube.dev https://logs.browser-intake-datadoghq.com; font-src 'self' https://fonts.gstatic.com https://static.cube.dev; frame-src 'self'; img-src 'self' data: https://static.cube.dev; manifest-src 'self'; media-src 'self'; worker-src 'none';"
+        }
+      ]
+    }
+  ]
+}