fix: remove invalid extra_head key and fix broken redirect target

- Remove extra_head (not a valid MkDocs config key, was breaking V2 build)
- Fix digital-money.md redirect: finops.md was deleted by publisher,
  redirect now points to kubernetes.md

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

v2-mkdocs.yml

@@ -82,7 +82,7 @@ plugins:
         dom.md: javascript.md
         react.md: javascript.md
         oauth.md: securityascode.md
-        digital-money.md: finops.md
+        digital-money.md: kubernetes.md
         aws-spain.md: aws.md
 
 extra:
@@ -96,9 +96,6 @@ extra:
   version:
     provider: mike # Ready for version switching
 
-extra_head:
-  - '<link rel="alternate" type="application/rss+xml" title="Nubenetes Intelligence Digest" href="/feed.xml"/>'
-
 extra_css:
   - https://fonts.googleapis.com/css2?family=Inter:wght@400;500;700&display=swap
   - static/extra.css