title: .gitignore still ignoring removed items
body: <p>I have a standard .gitignore file that I include in every project. One of the lines in there ignores "bin". </p>
  
  <p>It so happens, in this particular project, I actually <em>want</em> a /bin directory. I removed "bin" from .gitignore, but git still won't let me add the /bin directory. It still thinks it should ignore it, even though the string has been removed from .gitignore.</p>
  
  <p>All the answers I'm finding are about how to ignore something previously committed, but I'm not finding any info on how to add something previously ignored. </p>
  
  <p>So: How do I tell git to unignore something previously ignored?</p>