Update README.md

[arthurfaccioly]

This line:
$ jupyter contrib nbextension install --user

Caused an error on my mac:
(mlbook) macs-Mac-mini:dev mac$ jupyter contrib nbextension install --user
Error executing Jupyter command 'contrib': [Errno 2] No such file or directory

Then I used the following commands to adjust everything:
conda install -c conda-forge jupyter_contrib_nbextensions
conda install -c conda-forge jupyter_nbextensions_configurator

That I've got from this website:
https://ndres.me/post/best-jupyter-notebook-extensions/

So, my suggestion is to add those lines instead, mentioning that you can access the config website to activate whatever you want.

Merci.

[ageron]

Hi @arthurfaccioly ,

Thanks for your feedback, and sorry for the late response (I was traveling).
At the end of the "Using Anaconda" paragraph, there is already the following instruction:

conda install -n mlbook -c conda-forge jupyter_contrib_nbextensions

I'm guessing you did not run this line before executing jupyter contrib nbextension install --user?