Add Siamese Network example

Hi, I want to add an example for Siamese network, since it is one of the popular use cases in ML. I am thinking of implementing it in a way similar to other examples viz. command line arguments to choose which dataset to train, hyperparameters etc. Is there something I need to keep in mind specifically apart from these:

• Use torchvision's Dataset class and PyTorch's DataLoader class to handle data.
• Implement a simple CNN as a nn.Module subclass
• Implement triplet loss
• Create train and test functions and a main function that calls those 2 methods at each epoch.
• Report final loss and accuracy

Is this something that is worth adding to the repository.