title: How to change font size in geom_text() outside plot area?
body: <p>I'd like to annotate a plot and I'd like the note to be outside the plot area. I found <a href="https://stackoverflow.com/questions/12409960/ggplot2-annotate-outside-of-plot">this solution</a> and it works for adding a note outside the plot area, but I cannot figure out how to change the label's appearance (most importantly, for my purpose, the font size). </p>
  
  <p>Here is a minimal example from the aforementioned solution:</p>
  
  <pre><code>library (ggplot2)
  library(grid)
  
  df=data.frame(y=c("dog1","dog2","dog3"),x=c(12,10,14),n=c(5,15,20))
  p &lt;- ggplot(df, aes(x,y)) + geom_point()
  
  # Add the annotation
  p &lt;- p + geom_text(aes(label = "Hello World!", x = 0, y = 0), vjust = 2, hjust = 1)
  
  # Code to override clipping
  gt &lt;- ggplot_gtable(ggplot_build(p))
  gt$layout$clip[gt$layout$name == "panel"] &lt;- "off"
  grid.draw(gt)
  </code></pre>
  
  <p>Ideally, the note would be in the bottom left corner.</p>