docs: add Redis Checkpointer example (#961)

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Co-authored-by: Vadym Barda <vadim.barda@gmail.com>
Co-authored-by: Vadym Barda <vadym@langchain.dev>

docs/_scripts/copy_notebooks.py

@@ -30,6 +30,7 @@ _MANUAL = {
         "memory/add-summary-conversation-history.ipynb",
         "persistence_postgres.ipynb",
         "persistence_mongodb.ipynb",
+        "persistence_redis.ipynb",
         "visualization.ipynb",
         "state-model.ipynb",
         "subgraph.ipynb",