Remove misleading comment.

src/model.py

@@ -154,7 +154,7 @@ class ConditionalViT(nn.Module):
     def forward(self, imgs: torch.Tensor, c: torch.Tensor = None):
         """
         imgs : Batch of images
-        c : category indices. 0 = "No given category".
+        c : category indices.
         """
 
         x = self.conv1(imgs)  # shape = [*, width, grid, grid]