remove extraneous comma

Author: adqm

peps/pep-0798.rst

@@ -220,7 +220,7 @@ generator::
 Since ``yield from`` is not allowed inside of async generators (see the section
 of :pep:`525` on `Asynchronous yield from
 <https://peps.python.org/pep-0525/#asynchronous-yield-from>`__), the equivalent
-for ``(*expr async for x in ait())``, is more like the following (though of
+for ``(*expr async for x in ait())`` is more like the following (though of
 course this new form should not define or reference the looping variable
 ``i``)::