Typo

Author: calvingiles

Prologue/Prologue.ipynb

@@ -49,7 +49,7 @@
       "------\n",
       "\n",
       "(The below chapters are rendered via the *nbviewer* at\n",
-      "[nbviewer.ipython.org/](http://nbviewer.ipython.org/), and is read-only and rendered in real-time.\n",
+      "[nbviewer.ipython.org/](http://nbviewer.ipython.org/), and are read-only and rendered in real-time.\n",
       "Interactive notebooks + examples can be downloaded by cloning! )\n",
       "\n",
       "\n",