Add gisp2 example

+this is a readme file for the GISP2 ice core workshop example. This information is also presented at the start of the jupyter notebook (GISP2-MeekerMayewski2002-figurereproduction.ipynb)
+
+# Source Data
+- data was downloaded from <https://www.ncdc.noaa.gov/paleo-search/study/17805> on 6 March 2019 by Jessica Scheick
+- no checksums were available for the data, and data was downloaded as individual text files for the B and D (deep) cores, both detailed and non-detailed datasets (4 files total)
+- DIF metadata was downloaded separately (also available as a JSON file)
+- citation: Paul A. Mayewski, Loren D. Meeker, Mark S. Twickler, Sallie Whitlow, Qinzhao Yang, W. Berry Lyons, Michael Prentice. 1997. Major features and forcing of high-latitude northern hemisphere atmospheric circulation using a 110,000-year-long glaciochemical series. Journal of Geophysical Research: Oceans, 102(C12), 26345-26366. doi: 10.1029/96JC03365
+
+
+# Problem Statement and Objective
+- reproduce the figures containing ice core data located in Meeker and Mayewski (2002, full reference below)
+
+Paper Reference: Meeker, L.D. & Mayewski, P.A., 2002. A 1400-year high-resolution record of atmospheric circulation over the North Atlantic and Asia. The Holocene, 12(3), pp.257–266.
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