Include instructions for opening on Catalina

[amadeuspzs]

Open a terminal and run:

xattr -d com.apple.quarantine /Applications/Jupyter\ Notebook\ Viewer.app

You will now be able to load the app

[treese]

It should also work to right-click on the application in the finder and then hold the shift key while opening. That should only need to be done once.

[amadeuspzs]

Can confirm that you need the xattr command as shift right clicking doesn't work on latest Mac OS.