Document the notebooks

[NobleKennamer]

@arielkruger1989 @abhisaarsharma @dcockerham

If people could document the main notebooks RR_Lyrae.ipynb and redshift.ipynb so that the graders can easily follow everything that is happening that would be great.

Instead of adding comments into the executable cells create markdown cells directly above them to add the documentation. That looks a lot nicer. Plus the markdown cells support HTML so we can really make them look nice.

a good tutorial for adding this markdown can be found in the link below(it is actually really easy)

http://jupyter.cs.brynmawr.edu/hub/dblank/public/Jupyter%20Notebook%20Users%20Manual.ipynb