Add doctesting for new deletion in 0.2.1 versions

[rajivsarvepalli]

Improve documentation to add information inside the docstring for UnifiedAlchemyMagicMock to include testing for adding keywords argument to delete with no impact.

You can use keywords with delete like so:

n_d = s.query(Data).filter(Data.data_p1 >= 13).delete(synchronize_session=False)

and this will work. However, the keyword arguments have no impact on the delete command, but merely are allowed so as little code as possible has to be changed. However, delete cannot be used with objects such as:

a = Data(pk1=11, data_p1=31.5, data_p2=67.1, name="test13")
n_d = s.delete(a)

The above code is invalid when using UnifiedAlchemyMagicMock as the session object s.

[luizdepra]

Could be possible to mock session.delete(entity)? I think it will always conflict with entity.delete().

For now, I'm overriding the default implementation by doing this (assume I'm using AsyncSession):

session.delete = mock.AsyncMock()