Added jupyter to README (alshedivat#1637)

Signed-off-by: George Araujo <george.gcac@gmail.com>

README.md

@@ -238,10 +238,12 @@ $ docker-compose -f docker-local.yml up
 
 #### Local Setup (Standard)
 
-Assuming you have [Ruby](https://www.ruby-lang.org/en/downloads/) and [Bundler](https://bundler.io/) installed on your system (*hint: for ease of managing ruby gems, consider using [rbenv](https://github.com/rbenv/rbenv)*).
+Assuming you have [Ruby](https://www.ruby-lang.org/en/downloads/) and [Bundler](https://bundler.io/) installed on your system (*hint: for ease of managing ruby gems, consider using [rbenv](https://github.com/rbenv/rbenv)*), and also [Python](https://www.python.org/) and [pip](https://pypi.org/project/pip/) (*hint: for ease of managing python packages, consider using a virtual environment, like [venv](https://docs.python.org/pt-br/3/library/venv.html) or [conda](https://docs.conda.io/en/latest/). If you will use only `jupyter`, you can use [pipx](https://pypa.github.io/pipx/)*).
 
 ```bash
 $ bundle install
+# assuming pip is your Python package manager
+$ pip install jupyter
 $ bundle exec jekyll serve --lsi
 ```