Issue in tutorial

[FMassin]

Hello

This bit:

pyasdf/doc/tutorial.rst

Line 400 in ca35668

.. graphviz:: _static/example_waveform_simulation.dot

seems to be an issue fpr the web verison just above https://seismicdata.github.io/pyasdf/tutorial.html#reading-an-existing-asdf-data-set

I understand there no actual content missing (expect the viz itself) but maybe that worth being fix anyway.

Cheers

Fred