Tweaking checklist

Author: hadley

vignettes/development.Rmd

@@ -103,13 +103,14 @@ Pull requests will be evaluated against the following checklist:
 
 ```
 * [ ] Motivate the change in one paragraph, and include it in NEWS.
-      Reference this issue and thank yourself.
+      In parenthesis, reference your github user name and this issue:
+      `(@hadley, #1234)`
 * [ ] Check pull request only includes relevant changes.
 * [ ] Use the [official style](http://adv-r.had.co.nz/Style.html).
 * [ ] Update documentation and re-run roxygen2
 * [ ] Add test, if bug in non-graphical function
+* [ ] Add visual test, if bug in graphical function
 * [ ] Add minimal example, if new graphical feature
-* [ ] Does not change existing behaviour
 ```
 
 These are explained in more detail below. This seems like a lot of work but don't worry if your pull request isn't perfect. It's a learning process and Winston and I will be on hand to help you out. A pull request is a process, and unless you've submitted a few in the past it's unlikely that your pull request will be accepted as is.