title: rails link_to download file
body: <p>I need to add a link to download the file from assets/docs/Физика.pdf
  I do not know how to do that. 
  I am trying to do so here: in view -</p>
  
  <pre><code>&lt;%= link_to "download", '/Физика.pdf', :download =&gt; 'filename' %&gt;
  </code></pre>
  
  <p>I get an error message: </p>
  
  <pre><code>No route matches [GET] "/%D0%A4%D0%B8%D0%B7%D0%B8%D0%BA%D0%B0.pdf"
  </code></pre>
  
  <p>What am I doing wrong?
  Help me please</p>