Add examples how to mock objects

[maciekbanas]

With 3.2.1 it is reported that great functions local_mocked_bindings() (really, I love them, started to switch from mockery) can mock also objects.
Still, there is no example how to do it in function docs. Can you provide it?

[hadley]

Like local_mocked_bindings(x = 1) ?

[maciekbanas]

I'll try it :D