message: Fix odd number of backticks in docstring.
  This was causing the documentation to render incorrectly.
diff: @@ -71,7 +71,7 @@ class LinearOperatorKronecker(linear_operator.LinearOperator):
  `op1 x op2 x .. opJ` (we omit parentheses as the Kronecker product is
  associative).
  - If `opj` has shape `batch_shape_j` + [M_j, N_j`, then the composed operator
  + If `opj` has shape `batch_shape_j + [M_j, N_j]`, then the composed operator
  will have shape equal to `broadcast_batch_shape + [prod M_j, prod N_j]`,
  where the product is over all operators.
  