Fix markdown compiling issue
"source": [
"### A first kernel\n",
"\n",
- "To implement a custom kernel, we derive one from GPyTorch's [`kernel` class](https://docs.gpytorch.ai/en/latest/kernels.html) and implement the `forward()` method. The base class provides many useful routines. For example, `__call__()` is implemented, so that the kernel may be called directly, without resorting to the `forward()` routine. Among other things, the `Kernel` class provides a method `covar_dist()`, which may be used to calculate the Euclidian distance between point pairs conveniently.\n",
+ "To implement a custom kernel, we derive one from GPyTorch's [kernel class](https://docs.gpytorch.ai/en/latest/kernels.html) and implement the `forward()` method. The base class provides many useful routines. For example, `__call__()` is implemented, so that the kernel may be called directly, without resorting to the `forward()` routine. Among other things, the `Kernel` class provides a method `covar_dist()`, which may be used to calculate the Euclidian distance between point pairs conveniently.\n",
"\n",
"The `forward()` method represents the kernel function and should return a `torch.tensor` or a `gpytorch.lazy.LazyTensor`, when called on two `torch.tensor`s:"
]
