Updated svm_rbf docs with liquidSVM

Author: stevenpawley

R/svm_rbf.R

@@ -33,8 +33,15 @@
 #'  following _engines_:
 #' \itemize{
 #' \item \pkg{R}:  `"kernlab"` (the default)
+#' \item \pkg{R}:  `"liquidSVM"`
 #' }
 #'
+#' Note that models created using the `liquidSVM` engine cannot be saved like
+#' conventional R objects. The `fit` slot of the `model_fit` object has to be
+#' saved separately using the `liquidSVM::write.liquidSVM()` function. Likewise
+#' to restore a model, the `fit` slot has to be replaced with the model that is
+#' read using the `liquidSVM::read.liquidSVM()` function.
+#'
 #' @includeRmd man/rmd/svm-rbf.Rmd details
 #'
 #' @importFrom purrr map_lgl