Clean up frontend, DRY up templates

app/views/dictionary/show.html.erb

@@ -1,9 +1,10 @@
 <div>
-  <%= @letter.to_s %>
+  <h1><%= @letter.to_s %></h1>
 </div>
 
 <% @words.each do |word| %>
   <div>
-    <h1><%= word.word %></h1>
+    <h2><%= word.word %></h2>
+    <%= render "definitions", word: word %>
   </div>
 <% end %>