The fact is, that in official documentation Jupyter - motivating examples stands
Equation numbering and referencing will be available in a future vers
Go to your Jupyter Notebook editor (I am using Anaconda right now), Edit menu, the last item 'nbextensions config'. It opens a page where you can see a list of extensions, one of which is "Equation Auto Numbering". Enable it and restart your notebook. You will see that a button appears on the top of your notebook for resetting the numbering of equations. You will need to press that button every now and then.