docs: use real-world fineweb example for bucket copy CLI

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: mishig25

docs/hub/storage-buckets.md

@@ -279,11 +279,9 @@ You can copy [Xet](./xet/index)-tracked files from any repository (model, datase
 
 **CLI:**
 ```bash
-# Copy a file from a model repo to a bucket
-hf buckets cp hf://my-org/my-model/weights.safetensors hf://buckets/my-org/my-bucket/models/weights.safetensors
-
-# Copy an entire folder from a dataset to a bucket
-hf buckets cp hf://datasets/my-org/my-dataset/processed/ hf://buckets/my-org/my-bucket/dataset/processed/
+hf buckets cp \
+  hf://datasets/HuggingFaceFW/fineweb/data \
+  hf://buckets/{your_username}/fineweb-data
 ```
 
 **Python:**