title: rails_admin how to make a table name singular
body: <p>I am using rails_admin.</p>
  
  <p>My model is: </p>
  
  <pre><code>class Info &lt; ActiveRecord::Base
      set_table_name "info" 
  end
  </code></pre>
  
  <p>But in rails_admin It shows as <strong>Infos</strong>.
  How can I do it?</p>
  
  <p>Thanks</p>