Mention to install the tabulate module in README.org

Hello, I suggest mentioning to install the tabulate module when reading the Tip and Tricks section of the README. Just copy pasting the code snippet in a startup file and then trying to execute a code block using ob-ipython results in a cryptic json-read error which does not hint at the fact that the tabulate module might not be installed on the user's machine. Hence I suggest the following small change

"
ob-ipython will display anything back from ipython with the mime
type 'text/org' verbatim. This allows you and others to create
[[https://www.safaribooksonline.com/blog/2014/02/11/altering-display-existing-classes-ipython/][formatters]] that output raw org. For example, drop this in your
ipython startup file to have arrays and dataframes rendered as
org tables (make sure the [[https://pypi.org/project/tabulate/][tabulate]] module is installed via pip
or any package manager of your choice):
"