scout: unlist the scout metrics exporter page

Keeping this page unlisted while the feature goes through c0 evaluation

Signed-off-by: David Karlsson <35727626+dvdksn@users.noreply.github.com>

content/scout/metrics-exporter.md

@@ -1,5 +1,6 @@
 ---
 title: Docker Scout metrics exporter
+sitemap: false
 description: |
   Learn how to scrape data from Docker Scout using Prometheus to create your own
   vulnerability and policy dashboards wiht Grafana

data/toc.yaml

@@ -1404,8 +1404,6 @@ Manuals:
         title: SBOM
       - path: /scout/env-vars/
         title: Environment variables
-      - path: /scout/metrics-exporter/
-        title: Metrics exporter
     - sectiontitle: Policy Evaluation
       section:
       - path: /scout/policy/