fix: docs sitemap www prefix

Fixes the missing "www." prefix to the url in the
sitemap section of the docs website.

Signed-off-by: Tim Jones <tim.jones@siderolabs.com>

website/layouts/sitemap.xml

@@ -2,7 +2,7 @@
 <urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9" xmlns:xhtml="http://www.w3.org/1999/xhtml">
   {{- range .Data.Pages -}}{{ $currentVersion := index (split .Permalink "/" ) 1 }}{{ $currentVersionDir := $currentVersion | printf "/%s"}}{{ if and .Permalink (ne .Params.sitemap_exclude true) (eq $currentVersionDir site.Params.url_latest_version)}}
   <url>
-    <loc>https://sidero.dev{{ .Permalink }}</loc>{{ if not .Lastmod.IsZero }}
+    <loc>https://www.sidero.dev{{ .Permalink }}</loc>{{ if not .Lastmod.IsZero }}
     <lastmod>{{ safeHTML (.Lastmod.Format "2006-01-02T15:04:05-07:00") }}</lastmod>{{ end }}{{ with .Sitemap.ChangeFreq }}
     <changefreq>{{ . }}</changefreq>{{ end }}{{ if ge .Sitemap.Priority 0.0 }}
     <priority>{{ .Sitemap.Priority }}</priority>{{ end }}{{ if .IsTranslated }}{{ range .Translations }}