Update 2d List Tutorial

FIxes jdf/Processing.py-Bugs#259

Author: villares

Tutorials/2dlists/index.html

@@ -155,7 +155,7 @@ <h1>Two-Dimensional Lists</h1>
       </p>
       <img src="imgs/cells.jpg">
       <pre>
-      <a href="http://www.learningprocessing.com/examples/chapter-13/example-13-10/">Example: 2D Array of Objects</a>
+      <a href="http://learningprocessing.com/examples/chp13/example-13-10-grid-cells">Example: 2D Array of Objects</a>
         # Number of columns and rows in the grid
         nCols = 10;
         nRows = 10;
@@ -183,7 +183,7 @@ <h1>Two-Dimensional Lists</h1>
         def makeGrid():
             global nCols, nRows
             grid = []
-            for i in xrange(nRows):
+            for i in xrange(nCols):
                 # Create an empty list for each row
                 grid.append([])
                 for j in xrange(nRows):