title: R shiny break line in button label
body: <p>Please see the following toy example.
  Any help would be greatly appreciated! Thanks!</p>
  
  <pre><code>shinyApp(
  ui = fluidPage(
      actionButton("btnId", "I want a line break here &lt;br/&gt; since the label is too long")),
  server = function(input, output){})
  </code></pre>