Add Language model and LanguageController

app/views/layouts/application.html.erb

@@ -15,6 +15,10 @@
       <div class="d-flex mb-3">
         <div class="p-2">
           <%= link_to "Dictionary", dictionary_index_path %>
+          <% if user_signed_in? %>
+            <pre style="display: inline;">|</pre>
+            <%= link_to "Languages", languages_path %>
+          <% end %>
         </div>
         <div class="ms-auto p-2">
           <% if user_signed_in? %>