Upsert batch limit undocumented

[ArjunJagdale]

index.upsert() accepts any size list but throws ValueError: Cannot insert more than 1000 vectors at a time only after processing
Should either auto-batch internally or document the limit clearly in the method signature.

Good way for now -

    batch_size = 1000
    for i in range(0, len(vectors), batch_size):
        batch = vectors[i : i + batch_size]
        index.upsert(batch)
        print(f"UPSERTED batch {i // batch_size + 1} — {len(batch)} vectors")
    print(f"UPSERTED {len(vectors)} vectors")