title: Append text behind a certain keyword in filename
body: <p>In directory <code>C:\Users\Scripts</code>, I have files named:</p>
  
  <pre><code>2A_Apple_VC_20180101.txt
  2A_Apple_VC_20180201.txt
  2A_Apple_VC_20180301.txt
  etc.
  </code></pre>
  
  <p>How can I insert the phrase <code>Vendor</code> right after <code>2A_</code> for all the filenames in that directory that starts with <code>2A_</code>, permanently changing the filenames to:</p>
  
  <pre><code>2A_Vendor_Apple_VC_20180101.txt
  2A_Vendor_Apple_VC_20180201.txt
  2A_Vendor_Apple_VC_20180301.txt
  </code></pre>