docs: add MNIST magnitude pruning tutorial (#33)

* docs: add MNIST magnitude pruning tutorial

Adds a tutorial notebook demonstrating post-training and
fine-tuning-based magnitude pruning on an MNIST model, mirroring the
existing quantization and palettization tutorials. Also adds the
missing Pruning entry to the sidebar toctree.

* docs: use 70% sparsity for post-training pruning in MNIST tutorial

Aligns the post-training pruning section with the fine-tuning
section, which already targets 70% sparsity, instead of the default
50%.

* docs: use 50% sparsity in MNIST pruning tutorial, bake in outputs

Aligns post-training and fine-tuning sparsity at 50% and ships the
notebook with executed cell outputs, showing the actual effect of
pruning on accuracy end-to-end.

* docs: strip coremltools import warning from pruning tutorial output

Removes a local scikit-learn/coremltools version warning baked into
the notebook's output; it's environment noise, not tutorial content.

* docs: fix broken pruning config link in MNIST pruning tutorial

Author: u-simha

docs/src/examples/toy_models.md

@@ -8,4 +8,5 @@ These tutorials demonstrate model compression techniques using simple toy models
 /tutorials/mnist_quantization
 /tutorials/mnist_palettization
 /tutorials/mnist_palettization_and_activation_quantization
+/tutorials/mnist_pruning
 ```

docs/src/index.md

@@ -29,6 +29,7 @@ examples/model_examples
 
 quantization/index
 palettization/index
+pruning/index
 ```
 
 ```{toctree}