Python vs IPython: recommend %cd, %env over !cd, !export The quick overview mentioned `!cd DIR` among examples of shell commands one might use —but that doesn't work as user would hope (can only affect commands in same ! e.g. `!cd /; pwd`). That's not as bad now that `!cd` prints a warning, but IMHO better to provide the right mental model up front. => Replaced that with minimal motivation why `!cd` and `!export` can't work, recommending some %magic alternatives; moved it out of examples to not distract, and right before Magics section.