more docs + link fixing

layouts/_default/_markup/render-link.html

@@ -1,2 +1,7 @@
 {{$trimmed := strings.TrimSuffix ".md" (.Destination | safeURL)}}
-<a href="{{ if (hasPrefix $trimmed "/") }}{{ $trimmed }}{{ else }}{{ print "/" $trimmed }}{{ end }}" rel="noopener">{{ .Text | safeHTML }}</a>
+{{$external := strings.HasPrefix $trimmed "http" }}
+{{ if $external }}
+<a href="{{ $trimmed }}" rel="noopener">{{ .Text | safeHTML }}</a>
+{{else}}
+<a href="{{ if (hasPrefix $trimmed "/") }}{{ $trimmed }}{{ else }}{{ print "/" $trimmed }}{{ end }}" rel="noopener">{{ .Text | safeHTML }}</a>
+{{end}}