chore: remove footnotes in doc (#1662)

docs/advanced-topics/pruning.md

@@ -24,6 +24,4 @@ Fixing some of the weights to 0 makes the network graph look more similar to the
 
 ![Pruned Fully Connected Neural Network](../figures/prunednet.png)
 
-While pruning weights can reduce the prediction performance of the neural network, studies show that a high level of pruning (above 50% \[^1\]) can often be applied. See here how Concrete-ML uses pruning in [Fully Connected Neural Networks](../_apidoc/concrete.ml.sklearn.html#concrete.ml.sklearn.qnn.NeuralNetClassifier).
-
-\[^1\]: Han, Song & Pool, Jeff & Tran, John & Dally, William. (2015). Learning both Weights and Connections for Efficient Neural Networks.
+While pruning weights can reduce the prediction performance of the neural network, studies show that a high level of pruning (above 50%) can often be applied. See here how Concrete-ML uses pruning in [Fully Connected Neural Networks](../_apidoc/concrete.ml.sklearn.html#concrete.ml.sklearn.qnn.NeuralNetClassifier).