add readme for folder structure

Author: Adam M. Wilson

data/README.md

@@ -0,0 +1,11 @@
+Example folder structure for students to store class content.
+
+Note: to remove Mac related files from a zipped folder, run:
+
+`zip -d GEO503.zip __MACOSX/\*`
+
+`zip -d GEO503.zip \*/.DS_Store`
+
+Alternatively, compress the folder with (`-X` skips the hidden Mac files):
+
+`zip -r -X GEO503.zip GEO503`