In `project documentation`, add more details for `macOS` users about how to run the app (suggestion)

[pylapp]

Context

As a macOS user,
When I start the app,
I have a security warning
While I do not have details about what I should to to run the app

For example, I have first the pop-up:

And I needed to go in the security pane of my computer to allow it:

it could be explained in the documentation for people not used to this operation :-)