Fix missing titles on website docs.

Also fixes our sitemap to have correct `lastmod` times when built locally (it was already correct on Netlify).

Signed-off-by: Matt Moyer <moyerm@vmware.com>

site/content/docs/tutorials/_index.md

@@ -1,4 +1,5 @@
 ---
+title: Pinniped Tutorials
 cascade:
   layout: docs
 menu:
@@ -8,8 +9,6 @@ menu:
     weight: 40
 ---
 
-# Pinniped tutorials
-
 These tutorials demonstrate how to use the Pinniped command-line tool, Concierge, and Supervisor:
 
 {{< docsmenu "tutorials" >}}