fix code

docroot/posts/2019-07-17.01/article.pag

@@ -26,20 +26,20 @@ Not to forget it again I will summarize it here.
 <ol>
 <li>Create a file <tt>~/.screenrc</tt> and put
 
-<pre>
+<pre><code class="shell">
 setenv SSH_AUTH_SOCK $HOME/.ssh/SSH_AUTH_SOCK
-</pre>
+</code></pre>
 
 into it. If you are using bash, don't be tempted to write <tt>export</tt> instead of <tt>setenv</tt>, it won't work.
 </li>
 <li>
 Create a file <tt>~/.ssh/rc</tt> and put
 
-<pre>
+<pre><code class="shell">
 if test "$SSH_AUTH_SOCK" ; then
     ln -sf $SSH_AUTH_SOCK ~/.ssh/ssh_auth_sock
 fi
-</pre>
+</code></pre>
 
 into it.
 </li>