title: Custom column names in openxlsx
body: <p>I'm going to use openxlsx to generate a report.</p>
  <p>I have a dataframe with column names that aren't friendly to an end user. So I would like to generate an excel file with custom columns. I've figured out how to ignore column names using <code>colNames = FALSE</code>, but what is the best way to add names I need?</p>
  <pre><code>report &lt;- createWorkbook('report.xlsx')
  
  addWorksheet(report, 'test')
  
  # how to add column names
  
  writeData(report, sheet = 1, df, colNames = FALSE)
  
  saveWorkbook(report, 'report.xlsx', overwrite = TRUE)
  </code></pre>