In Nbconvert Support.ipynb raw cell example should use \frac not \\frac

[Szepi]

At least in my install, \frac{} in the last cell produces correct html, not \frac. Config:

%%bash
python -V
jupyter --version
jupyter nbconvert --version

Python 3.5.3
4.3.0
5.1.1

Oh, the browser does not seem to make a difference (Firefox, Chrome tested).