minor fix in docstrings of TorchTensorDotLayer

cirkit/backend/torch/layers/optimized.py

@@ -196,9 +196,11 @@ class TorchTensorDotLayer(TorchInnerLayer):
     and $K_i$ is the number of input uits. The tensor dot layer firstly reshapes as the tensor
     $\mathcal{Z}$ having shape $(B, K_j, K_q)$, where $K_i = K_jK_q$. Then, it computes the
     tensor $\mathcal{S}$ of shape $(B, K_q, K_k)$ as follows:
+
     $$
     \mathcal{S}_{bqk} = \sum_{j=1}^{K_j} w_{kj} z_{bjq}
     $$
+
     in element-wise notation, where $\mathbf{W}$ is a tensor of shape $(K_k, K_j)$,
     where we have that $K_o = K_qK_k$ is the number of output units.
     Finally, it returns the output tensor of shape $(B, K_o)$ obtained by flattening the