Stackless issue python#237: Fix doc-string of tasklet.throw

The 4th argument has been changed from immediate=True to pending=False
a long time ago.

(cherry picked from commit 12b78b0)

Author: Anselm Kruis

Stackless/module/taskletobject.c

@@ -1280,7 +1280,7 @@ tasklet_setup(PyObject *self, PyObject *args, PyObject *kwds)
 
 
 PyDoc_STRVAR(tasklet_throw__doc__,
-             "tasklet.throw(exc, val=None, tb=None, immediate=True) -- raise an exception for the tasklet.\n\
+             "tasklet.throw(exc, val=None, tb=None, pending=False) -- raise an exception for the tasklet.\n\
              'exc', 'val' and 'tb' have the same semantics as the 'raise' statement of the Python(r) language.\n\
              If 'pending' is True, the tasklet is not immediately activated, just\n\
              merely made runnable, ready to raise the exception when run.");