Fix datasets missing versions (#318)

lerobot/common/datasets/push_dataset_to_hub/CODEBASE_VERSION.md

@@ -0,0 +1,57 @@
+## Using / Updating `CODEBASE_VERSION` (for maintainers)
+
+Since our dataset pushed to the hub are decoupled with the evolution of this repo, we ensure compatibility of
+the datasets with our code, we use a `CODEBASE_VERSION` (defined in
+lerobot/common/datasets/lerobot_dataset.py) variable.
+
+For instance, [`lerobot/pusht`](https://huggingface.co/datasets/lerobot/pusht) has many versions to maintain backward compatibility between LeRobot codebase versions:
+- [v1.0](https://huggingface.co/datasets/lerobot/pusht/tree/v1.0)
+- [v1.1](https://huggingface.co/datasets/lerobot/pusht/tree/v1.1)
+- [v1.2](https://huggingface.co/datasets/lerobot/pusht/tree/v1.2)
+- [v1.3](https://huggingface.co/datasets/lerobot/pusht/tree/v1.3)
+- [v1.4](https://huggingface.co/datasets/lerobot/pusht/tree/v1.4)
+- [v1.5](https://huggingface.co/datasets/lerobot/pusht/tree/v1.5) <-- last version
+- [main](https://huggingface.co/datasets/lerobot/pusht/tree/main) <-- points to the last version
+
+Starting with v1.6, every dataset pushed to the hub or saved locally also have this version number in their
+`info.json` metadata.
+
+### Uploading a new dataset
+If you are pushing a new dataset, you don't need to worry about any of the instructions below, nor to be
+compatible with previous codebase versions. The `push_dataset_to_hub.py` script will automatically tag your
+dataset with the current `CODEBASE_VERSION`.
+
+### Updating an existing dataset
+If you want to update an existing dataset, you need to change the `CODEBASE_VERSION` from `lerobot_dataset.py`
+before running `push_dataset_to_hub.py`. This is especially useful if you introduce a breaking change
+intentionally or not (i.e. something not backward compatible such as modifying the reward functions used,
+deleting some frames at the end of an episode, etc.). That way, people running a previous version of the
+codebase won't be affected by your change and backward compatibility is maintained.
+
+However, you will need to update the version of ALL the other datasets so that they have the new
+`CODEBASE_VERSION` as a branch in their hugging face dataset repository. Don't worry, there is an easy way
+that doesn't require to run `push_dataset_to_hub.py`. You can just "branch-out" from the `main` branch on HF
+dataset repo by running this script which corresponds to a `git checkout -b` (so no copy or upload needed):
+
+```python
+from huggingface_hub import HfApi
+
+from lerobot import available_datasets
+from lerobot.common.datasets.lerobot_dataset import CODEBASE_VERSION
+
+api = HfApi()
+
+for repo_id in available_datasets:
+    dataset_info = api.list_repo_refs(repo_id, repo_type="dataset")
+    branches = [b.name for b in dataset_info.branches]
+    if CODEBASE_VERSION in branches:
+        # First check if the newer version already exists.
+        print(f"Found existing branch for {repo_id}. Please contact a member of the core LeRobot team.")
+        print("Exiting early")
+        break
+    else:
+        # Now create a branch named after the new version by branching out from "main"
+        # which is expected to be the preceding version
+        api.create_branch(repo_id, repo_type="dataset", branch=CODEBASE_VERSION, revision="main")
+        print(f"{repo_id} successfully updated")
+```