Merge pull request #839 from CoffeaTeam/mltools-doc-cleanup

fix: remove now-incorrect documentation from ml_tools

src/coffea/ml_tools/helper.py

@@ -188,26 +188,6 @@ def prepare_awkward(self, *args, **kwargs) -> Tuple:
         Consult the following documentation to find the awkward operations
         needed.
             https://awkward-array.org/doc/main/user-guide/how-to-restructure-pad.html
-
-        If you need to use numpy-only operations like np.column_stack, remember to use
-        awkward.typetracer.length_zero_if_typetracer(arg) before calling .to_numpy().
-        Furthermore you should convert back into a typetracer in these situations.
-        Otherwise, when running with dask_awkward, you will run into problems.
-
-        length_zero_if_typetracer and typetracer handling example:
-            def prepare_prepare_awkward(self, events):
-            ret = np.column_stack(
-                [
-                    ak.typetracer.length_zero_if_typetracer(events[name])
-                    for name in feature_list
-                ]
-            )
-            ret = ak.Array(ret, behavior=events.behavior)
-            if ak.backend(events) == "typetracer":
-                ret = ak.Array(
-                    ret.layout.to_typetracer(forget_length=True), behavior=ret.behavior
-                )
-            return [], dict(data=ret)
         """
         pass