Provide example of @pytest.fixure that is flaky

I tried to do this

```
@pytest.fixture
@pytest.mark.flaky
def the_server(
```

But it didn't seem to work as I expected.  Is that the right way of doing it as I don't see it in the readme

Perhaps something on this page https://pytest-rerunfailures.readthedocs.io/latest/mark.html