I'm looking for a gi.repository module documentation and I can't find anything on the internet.
All I found is documentation of new Gtk3 libraries for C, or old PyGtk 2.0 Reference Manual
I'm looking for something like PyGtk 2.0 Reference Manual but for Gtk3.
Is there something similar for Python? (I'm not looking for dir(Gtk) or help(Gtk) in the Python console.)
I think you're looking for this.
It's a work in progress, but basically is a tutorial for Gtk3 in python. I doesn't really cover any other thing aside from Gtk widgets (so no Glib, for example), but it's still useful to get started.