[megatron] fix: correct typo in modeling_qwen2_megatron.py (verl-project#4486)

### What does this PR do?

> This PR corrects a spelling error in the docstring of the
`setup_embeddings_and_output_layer` method within
`verl/models/qwen2/megatron/modeling_qwen2_megatron.py`. Specifically,
it changes `initalizes` to `initializes`.

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  - Title: `[megatron] fix: correct typo in modeling_qwen2_megatron.py`

### Test

> This is a trivial documentation fix (docstring only) and does not
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### API and Usage Example

> N/A - This change only affects internal code documentation.

### Design & Code Changes

> **Modifications:**
> - `verl/models/qwen2/megatron/modeling_qwen2_megatron.py`: Fixed typo
`initalizes` -> `initializes`.

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Author: study8677

verl/models/qwen2/megatron/modeling_qwen2_megatron.py

@@ -583,7 +583,7 @@ def _init_head(self, config):
     def setup_embeddings_and_output_layer(self) -> None:
         """Sets up embedding layer in first stage and output layer in last stage.
 
-        This function initalizes word embeddings in the final stage when we are
+        This function initializes word embeddings in the final stage when we are
         using pipeline parallelism and sharing word embeddings, and sets up param
         attributes on the embedding and output layers.
         """