Add links at start and end of train_a_model and upload_a_model docs

examples/tutorials/curation/plot_2_train_a_model.py

@@ -163,4 +163,4 @@
 #
 # Now that you have a model, you can `apply it to another sorting
 # <https://spikeinterface.readthedocs.io/en/latest/tutorials/curation/plot_1_automated_curation.html>`_
-# or upload it to `HuggingFaceHub <https://huggingface.co/>`_.
+# or `upload it to HuggingFaceHub <https://spikeinterface.readthedocs.io/en/latest/tutorials/curation/plot_3_upload_a_model.html>`_.

examples/tutorials/curation/plot_3_upload_a_model.py

@@ -6,6 +6,8 @@
 # In this tutorial we will upload a pipeline, trained in SpikeInterface, to the
 # `Hugging Face Hub <https://huggingface.co/>`_ (HFH).
 #
+# To do this, you first need to train a model. `Learn how here! <https://spikeinterface.readthedocs.io/en/latest/tutorials/curation/plot_2_train_a_model.html>`_
+#
 # Hugging Face Hub?
 # -----------------
 # Hugging Face Hub (HFH) is a model sharing platform focused on AI and ML models and datasets.