package: navigate with index.html explicitly (#840)

On object storage, directory index is not available, so use generated
DIRECTORY/index.html explicitly.

Signed-off-by: Kentaro Hayashi <[email protected]>

Author: kenhys

fluent-package/make-index-html.erb

@@ -36,7 +36,7 @@
            <% end %>
            <% files.each do |file| %>
              <% if File.directory?(file) %>
-               <li><a href="/<%= relative_path %>/<%= file %>"><i class="ri-folder-line"></i> <%= file %></span></a>
+               <li><a href="/<%= relative_path %>/<%= file %>/index.html"><i class="ri-folder-line"></i> <%= file %></span></a>
              <% else %>
                <li><a href="/<%= relative_path %>/<%= file %>"><i class="ri-file-download-line"></i> <%= file %></span></a>
                <%= sprintf("%.2f", File.stat(file).size / 1024 / 1024.0) %> MiB