Documentation improvement: Re-add "how to download .ipynb" instructions to Illumina Overview Tutorial webpage

[AmandaBirmingham]

Once upon a time (apparently as recently as release 1.8.0, see http://qiime.org/1.8.0/tutorials/illumina_overview_tutorial.html ), the Illumina Overview Tutorial html page had a prominent red banner instructing users how to download the actual, runable .ipynb file rather than the html version of it (still confusingly named with a .ipynb extension) available through nbviewer; see first screenshot. However, this banner is not there on the current version of the Illumina Overview Tutorial page (at http://qiime.org/tutorials/illumina_overview_tutorial.html, see second screenshot). The banner info is really useful info, especially for the beginners at whom this overview tutorial is aimed, so it would be very nice to have it reinstated. Note that the page lacking the red banner is the one that comes up as the very first google hit in a search for "qiime illumina overview" as well as being the version linked to by http://qiime.org/tutorials/index.html , and so is the most likely landing place for newbies.

[souravsingh]

I would like to work on this issue.