docs: Make the tools content page a section page

Because it is the right solution and it the avoids naming conflict with section vs page.

Updates #2297

docs/content/tools/_index.md

@@ -1,5 +1,4 @@
 ---
-lastmod: 2015-12-30
 date: 2015-09-12T10:40:31+02:00
 title: Tools
 weight: 120

docs/layouts/_default/list.html

@@ -1,4 +1,7 @@
 {{ define "main" }}
+{{ with .Content }}
+{{ . }}
+{{ end }}
 <ul style="margin-top: 20px">
     {{ range .Data.Pages }}
     <li>