feat: add gemma 3 in readme and tutorials (#2005)

Author: k223kim

README.md

@@ -123,6 +123,7 @@ Every model is written from scratch to maximize performance and remove layers of
 | Function Calling Llama 2 | 7B | Trelis | [Trelis et al. 2023](https://huggingface.co/Trelis/Llama-2-7b-chat-hf-function-calling-v2)                                  |
 | Gemma | 2B, 7B | Google | [Google Team, Google Deepmind](https://storage.googleapis.com/deepmind-media/gemma/gemma-report.pdf)                                       |
 | Gemma 2 | 9B, 27B | Google | [Google Team, Google Deepmind](https://storage.googleapis.com/deepmind-media/gemma/gemma-2-report.pdf)                                  |
+| Gemma 3 | 1B, 4B, 12B, 27B | Google | [Google Team, Google Deepmind](https://arxiv.org/pdf/2503.19786)                                  |
 | Llama 2 | 7B, 13B, 70B | Meta AI | [Touvron et al. 2023](https://arxiv.org/abs/2307.09288)                                                                           |
 | Llama 3.1 | 8B, 70B | Meta AI | [Meta AI 2024](https://github.com/meta-llama/llama3)                                                                                 |
 | Llama 3.2 | 1B, 3B | Meta AI | [Meta AI 2024](https://ai.meta.com/blog/llama-3-2-connect-2024-vision-edge-mobile-devices/)                                           |

tutorials/download_model_weights.md

@@ -17,6 +17,7 @@ LitGPT supports a variety of LLM architectures with publicly available weights.
 | Function Calling Llama 2 | 7B | Trelis | [Trelis et al. 2023](https://huggingface.co/Trelis/Llama-2-7b-chat-hf-function-calling-v2)                                  |
 | Gemma | 2B, 7B | Google | [Google Team, Google Deepmind](https://storage.googleapis.com/deepmind-media/gemma/gemma-report.pdf)                                       |
 | Gemma 2 | 2B, 9B, 27B | Google | [Google Team, Google Deepmind](https://storage.googleapis.com/deepmind-media/gemma/gemma-2-report.pdf)                              |
+| Gemma 3 | 1B, 4B, 12B, 27B | Google | [Google Team, Google Deepmind](https://arxiv.org/pdf/2503.19786)
 | Llama 2 | 7B, 13B, 70B | Meta AI | [Touvron et al. 2023](https://arxiv.org/abs/2307.09288)                                                                           |
 | Llama 3 | 8B, 70B | Meta AI | [Meta AI 2024](https://github.com/meta-llama/llama3)                                                                                   |
 | Llama 3.1 | 8B, 70B, 405B | Meta AI | [Meta AI 2024](https://github.com/meta-llama/llama3)                                                                           |
@@ -119,6 +120,10 @@ garage-bAInd/Platypus2-70B-instruct
 garage-bAInd/Platypus2-7B
 garage-bAInd/Stable-Platypus2-13B
 google/codegemma-7b-it
+google/gemma-3-27b-it
+google/gemma-3-12b-it
+google/gemma-3-4b-it
+google/gemma-3-1b-it
 google/gemma-2-27b
 google/gemma-2-27b-it
 google/gemma-2-2b