`Command Summary`: Pull doesn't exists

I also don't fully understand the use case (the name is kind of confusing), given the explained usage in [Modifying annotations in existing datasets](https://github.com/iterative/ldb-resources/blob/main/documentation/Getting-started-with-LDB.md#modifying-annotations-in-existing-datasets):

>
>
> Step | Command
> -- | --
> List all objects matching annotation field in the index | $ ldb index gs://iterative/handwritten-reannotated/
>
> However, as we mentioned, this change would not affect the existing datasets that are referencing the older annotations. To upgrade all annotations in a dataset to the latest revision found in index, one can use PULL command:
>
>
> Step | Command
> -- | --
> Bump annotations to the latest version | $ ldb pull

Would, in this case, the result be equivalent to:

```console
$ ldb add gs://iterative/handwritten-reannotated/
$ ldb commit
```

If so, I think I would need to see another use case to consider having a separate command valuable enough.