docs: rephrase the sentence for specific loss function (#436)

nbs/docs/getting-started/1_introduction.ipynb

@@ -24,7 +24,7 @@
     "\n",
     "* **[Multiple Series Forecasting](https://docs.nixtla.io/docs/tutorials-multiple_series_forecasting)**: Simultaneously forecast multiple time series data, optimizing workflows and resources.\n",
     "\n",
-    "* **[Custom Loss Function](https://docs.nixtla.io/docs/tutorials-fine_tuning_with_a_specific_loss_function)**: Tailor the fine-tuning process with a custom loss function to meet specific performance metrics.\n",
+    "* **[Specific Loss Function](https://docs.nixtla.io/docs/tutorials-fine_tuning_with_a_specific_loss_function)**: Tailor the fine-tuning process by choosing from many loss functions to meet specific performance metrics.\n",
     "\n",
     "* **[Cross-validation](https://docs.nixtla.io/docs/tutorials-cross_validation)**: Implement out of the box cross-validation techniques to ensure model robustness and generalizability.\n",
     "\n",