refactor: optimize nested loop in module template rendering

Author: yordis

lib/ex_doc/formatter/markdown/templates/module_template.eex

@@ -6,9 +6,7 @@
 > This <%= module.type %> is deprecated. <%=h deprecated %>.
 <% end %>
 <%= node_doc(module) %>
-<%= for {_name, nodes} <- docs do %>
-<%= for node <- nodes do %>
+<%= for {_name, nodes} <- docs, node <- nodes do %>
 <%= detail_template(node, module) %>
 <% end %>
-<% end %>
 <%= before_closing_body_tag(config, :markdown) %>