bugfix: nested sidebar_root_for

Previously, when attempting to use nested sidebar_root_for directives,
the sidebar root displayed would be inconsistent for nested "self"
directives, and ineffective for nested "children" directives.

Investigation pointed to searching the ancestors collection in reverse
order.

Hugo documentation for the Ancestors method states:
> Hugo orders the ancestors from closest to furthest.

See https://gohugo.io/methods/page/ancestors/.

The list returned by the Anscestors list is already in "reverse" order;
calling Reverse on it gives a list with the root first, meaning that we
will find the highest-level sidebar_root_for page, rather than the
lowest level.

This commit removes the Reverse directive. sidebar_root_for directives
can now be nested correctly.

Author: reidmv

layouts/_partials/sidebar.html

@@ -17,7 +17,7 @@
     {{ $sidebarRoot = . -}}
   {{ else -}}
     {{/* Check ancestors for sidebar_root_for (any value) */ -}}
-    {{ range .Ancestors.Reverse -}}
+    {{ range .Ancestors -}}
       {{ if not .IsSection -}}
         {{ continue -}}
       {{ end -}}