Merge pull request gumption#2 from Ogaday/master

Corrects typo and resolves gumption#1

Author: gumption

README.md

@@ -7,7 +7,7 @@ The primer is spread across a collection of [IPython Notebooks](http://ipython.o
 There are four versions of the primer. Three versions contain the entire primer in a single notebook:
 
 * Single IPython Notebook (cleared output cells): [Python_for_Data_Science_clean.ipynb](Python_for_Data_Science_clean.ipynb)
-* Single IPython Notebook (filled output cells): [Python_for_Data_Science_clean.ipynb](Python_for_Data_Science_all.ipynb)
+* Single IPython Notebook (filled output cells): [Python_for_Data_Science_all.ipynb](Python_for_Data_Science_all.ipynb)
 * Single web page (HTML): [Python_for_Data_Science_all.html](Python_for_Data_Science_all.html)
 
 The other version divides the primer into 5 separate notebooks:
@@ -56,4 +56,4 @@ There are also 2 data files, based on the [mushroom dataset](https://archive.ics
 * Changed ["call by reference"](https://en.wikipedia.org/wiki/Evaluation_strategy#Call_by_reference) to ["call by sharing"](https://en.wikipedia.org/wiki/Evaluation_strategy#Call_by_sharing)
 * Added `isinstance()` (and reference to duck typing) to section on `type()`
 * Added variable for `delimiter` rather than hard-coding `'|'` character
-* Cleaned up various cells
+* Cleaned up various cells