Updated docstring examples to use cleaner callable syntax:
- sigmoid(x) instead of sigmoid.forward(x)
- relu(x) instead of relu.forward(x)
- tanh(x) instead of tanh.forward(x)
- gelu(x) instead of gelu.forward(x)
- softmax(x) instead of softmax.forward(x)
This demonstrates the proper usage pattern with the __call__ methods
we just added, making examples more Pythonic and PyTorch-compatible.