title: Submitting package to CRAN: Warnings in devtools:vignette_build()
body: <p>I am planning to submit a package to CRAN. I have no errors, warnings, or notes in check(). However, I do have warnings in vignette_build(). These warnings are simply due to my example dataset having NAs for some rows, which get removed.</p>
  
  <p>Is this something I should add a comment about to CRAN? Or, would that be something that they will not see and/or will not care about?</p>