title: Link command line tf checkin to work item
body: <p>I'd like to commit a file to TFS repository through the <code>tf</code> command-line tool and link the commit to a TFS work-item.  How do I do it?</p>
  
  <p>I've gotten as far as committing my file, but without a link to the work-item.  </p>
  
  <p>My command adds a new file and commits the changes:</p>
  
  <pre><code>%&gt; tf add foo.cpp
  %&gt; tf checkin foo.cpp -comment:"this is cool, but no work-item!"
  </code></pre>