Clarify PP split point documentation.

[githubsgi]

Bug description

The current documentation is as follows.

        self.parser.add_argument(
            "--parallelism.pipeline_parallel_split_points",
            type=string_list,
            nargs="+",
            default=[],
            help="""
                Specify comma-separated names of modules to use as the beginning of a split point.

                e.g. "layers.0,layers.2" will cause the model to be split into 3 stages,
                the first containing all the layers up to layers.0,
                the second containing layers.0 and up to layers.2,
                the third containing layers.2 and all the remaining layers.

                Note: fully-automated splitting may be enabled in the future,
                but currently the split points must be specified manually.""",
        )

The above description seems to indicate that layer.0 is present in both the first and second stages, layer.2 is present in both second and third stages. Can someone please clarify inclusivity ?

Versions

head of master

[tianyu-l]

cc @H-Huang