added jupyter cite to jupyter chapter bug hunt py issue

Author: trevorcampbell

source/jupyter.Rmd

@@ -68,7 +68,7 @@ By the end of the chapter, readers will be able to do the following:
 
 ## Jupyter
 
-Jupyter is a web-based interactive development environment for creating, editing,
+Jupyter [@kluyver2016jupyter] is a web-based interactive development environment for creating, editing,
 and executing documents called Jupyter notebooks. Jupyter notebooks \index{Jupyter notebook} are
 documents that contain a mix of computer code (and its output) and formattable
 text. Given that they combine these two analysis artifacts in a single