title: How to use OnChange() trigger
body: <p>I have a spreadsheet, as well as a master copy of the spreadsheet.
  Every time user enters data into a cell, it takes the new data and throw into the master copy.</p>
  
  <p>Recently however, I noticed a user creating a new column, which was not captured by OnEdit().</p>
  
  <p>Hence I looked it up and saw OnChange(), which was implemented last year.</p>
  
  <p>However, I do not know how to use that trigger.</p>
  
  <p>How do I retrieve the new column or row, or the merged cells that the user changed, and duplicate it into my master copy? I can't find documentation on this.</p>