Remove unneeded import of IPython.display.display

This is built-in in newer versions of IPython.

Author: mgeier

doc/code-cells.ipynb

@@ -165,15 +165,6 @@
     "TODO: tables? e.g. Pandas DataFrame?"
    ]
   },
-  {
-   "cell_type": "code",
-   "execution_count": null,
-   "metadata": {},
-   "outputs": [],
-   "source": [
-    "from IPython.display import display"
-   ]
-  },
   {
    "cell_type": "markdown",
    "metadata": {},
@@ -600,7 +591,7 @@
    "name": "python",
    "nbconvert_exporter": "python",
    "pygments_lexer": "ipython3",
-   "version": "3.6.7"
+   "version": "3.7.1"
   }
  },
  "nbformat": 4,