Some TestBase documentation code example lines got shifted

[qstokkink]

After #1193, the Unit Testing Overlays documentation has had some of its code examples shifted down by two lines. For example:

            super().patch_overlays(i)

    async def test_call(self) -> None:
        """
        Create a MyCommunity and check the output of some_constant().
        """
        # Create 1 MyCommunity
        self.initialize(MyCommunity, 1)

        # Nodes are 0-indexed
        value = self.overlay(0).some_constant()

It may only be this one file and a handful of examples but this is the main portal for new developers and this should be corrected quickly: high priority.