Fix "Source" text for the "Other Syntax" section of the notebook

Before it was shown as the "Display" one because of a missing end of
line.

examples/notebooks/Typesetting Math Using MathJax.ipynb

@@ -193,7 +193,8
       "You will notice in other places on the web that `$$` are needed explicitly to begin and end MathJax typesetting.  This is **not** required if you will be using TeX environments, but the IPython notebook will accept this syntax on legacy notebooks.  \n",
       "\n",
       "### Source\n",
-      "```$$\n",
+      "```\n",
+      "$$\n",
       "\\begin{array}{c}\n",
       "y_1 \\\\\\\n",
       "y_2 \\mathtt{t}_i \\\\\\\n",