**Note**: This is not a breaking change; "legacy" grids were deprecated
pre v1.0.

…batch

…Kernel

- The functionality of both kernels has not disappeared, but both
  kernels cannot work without the last_dim_is_batch_option.
- The examples/00_Basic_Usage/kernels_with_additive_or_product_structure.ipynb
  notebook describes how to replicate the functionality of both kernels
  without last_dim_is_batch.

- The functionality of this kernels has not disappeared, but this
  kernel cannot work without the last_dim_is_batch_option.
- The examples/00_Basic_Usage/kernels_with_additive_or_product_structure.ipynb
  notebook describes how to replicate the functionality of this kernel
  using the gpytorch.utils.sum_interaction_terms utility.