title: Webpack Bootstrap 4 copy custom.scss file to node_modules
body: <p><strong>Background:</strong>
  Bootstrap 4 has a file called _custom.scss where you can override the variables for the bootstrap framework for a custom theme. </p>
  
  <p>I was able to get this working using gulp by copying a file in my project called "bootstrap-overrides.scss" and replacing the "_custom.scss" file with it's contents prior to compiling it. That solved my problems (using gulp).</p>
  
  <p><strong>Issue:</strong>
  I am now trying to accomplish the same thing using webpack and I am having issues. I need this to happen BEFORE any of the bundling begins. <strong><em>All I need to do is copy "./source/bootstrap-overrides.scss" to "./node_modules/bootstrap/scss/_custom.scss".</em></strong> </p>
  
  <p>I tried to accomplish this using the <em>copy-webpack-plugin</em>; however, it keeps dumping my files into the output path directory instead of the node_modules folder.</p>
  
  <p>Any webpack gurus out there have any advice on how to do this? </p>
  
  <p>Thank you in advance!</p>