Update/simplify renovate config header comment

The previous comment included way too many details.  It also referenced
a docker-hub container image which is not accessible under all
circumstances.  Switch to the GitHub container registry and include
mention of the pre-commit hook that's available.

Signed-off-by: Chris Evich <cevich@redhat.com>

.github/renovate.json5

@@ -1,32 +1,13 @@
 /*
-   Renovate is a service similar to GitHub Dependabot, but with
-   (fantastically) more configuration options.  So many options
-   in fact, if you're new I recommend glossing over this cheat-sheet
-   prior to the official documentation:
 
-   https://www.augmentedmind.de/2021/07/25/renovate-bot-cheat-sheet
+Validate this file before commiting with (from repository root):
 
-   Configuration Update/Change Procedure:
-     1. Make changes
-     2. Manually validate changes (from repo-root):
+    podman run -it \
+        -v ./.github/renovate.json5:/usr/src/app/renovate.json5:z \
+        ghcr.io/renovatebot/renovate:latest \
+        renovate-config-validator
 
-        podman run -it \
-            -v ./.github/renovate.json5:/usr/src/app/renovate.json5:z \
-            docker.io/renovate/renovate:latest \
-            renovate-config-validator
-     3. Commit.
-
-   Configuration Reference:
-   https://docs.renovatebot.com/configuration-options/
-
-   Monitoring Dashboard:
-   https://app.renovatebot.com/dashboard#github/containers
-
-   Note: The Renovate bot will create/manage it's business on
-         branches named 'renovate/*'.  Otherwise, and by
-         default, the only the copy of this file that matters
-         is the one on the `main` branch.  No other branches
-         will be monitored or touched in any way.
+and/or use the pre-commit hook: https://github.com/renovatebot/pre-commit-hooks
 */
 
 {