title: Rename parts of file names that match a pattern
body: <p>Say I have a list of file names like this:</p>
  
  <pre><code>some-file.ts  
  my-project-service.ts  
  other.ts  
  something-my-project.ts 
  </code></pre>
  
  <p>I need to change the file names that have <code>my-project</code> in them to have just that part renamed to <code>$appname$</code>.  </p>
  
  <p>So <code>my-project-service.ts</code> would become <code>$appname$-service.ts</code></p>
  
  <p>And I need to do this recursively from a root directory.</p>
  
  <p>I seem to be to be hopeless at PowerShell so I thought I would ask here to see if anyone can help me out. </p>