Update static ReadTheDocs pages to correspond with current master

[fluegelk]

At the end of Tutorial 1, Section 1, it says "The output looks like this:". However, following only this tutorial up to this point, one would not get any output at all as python's default logging level is logging.WARNING, and one is never instructed to set the logging level or call propulate.utils.set_logger_config().

[mcw92]

Thanks for your comment! I think this is only the case for the linked ReadTheDocs page which is not yet updated (this will hopefully happen very soon). The actual script in the Github repo (which should also be linked on the RTD page at the very top) uses the logger. I will change the title of this issue to "Updating static ReadTheDocs pages to current master stage" and assign myself to it. There will be a complete rework of RTD once other things (parallel checkpointing with hdf5, new solvers, more comprehensive tests, etc.) will be merged and we have a new PyPI release.