theme specification for captions not used in ggplot2 examples

In the [ggplot2 examples](https://allisonhorst.github.io/palmerpenguins/articles/examples.html) there are some theme specifications for captions, e.g.

```r
plot.caption = element_text(hjust = 0, face= "italic"),
plot.caption.position = "plot"
```

I believe these are not used since the plots don't have captions. Were they supposed to have captions or should these be removed? I'm happy to send in a PR but I wasn't sure which way to go. 🐧