Fix typos in Gemma 4 Assistant documentation
Author: RaunaqDavidNath
Pull request: yes

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# What does this PR do?

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Fixes # (issue)

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### CI recap

**Dashboard:** [View test results in Grafana](https://transformers-ci.lor-e.huggingface.cool/d/pytest-observability-by-pr/pytest-observability-branch?var-pr=46975)
**Latest run:** [28428158728:2](https://github.com/huggingface/transformers/actions/runs/28428158728)
**Result:** `success` | **Jobs:** 2 | **Tests:** 9 | **Failures:** 0 | **Duration:** 45s

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Comments:
The docs for this PR live [here](https://moon-ci-docs.huggingface.co/docs/transformers/pr_46975). All of your documentation changes will be reflected on that endpoint. The docs are available until 30 days after the last update.