update docs for collapse rows.
diff --git a/R/collapse_rows.R b/R/collapse_rows.R
index 0004ec8..f9602e8 100644
--- a/R/collapse_rows.R
+++ b/R/collapse_rows.R
@@ -1,6 +1,14 @@
#' Collapse repeated rows to multirow cell
#'
-#' @description
+#' @description Collapse same values in columns into multirow cells. This
+#' feature does similar things with `group_rows`. However, unlike `group_rows`,
+#' it analyzes existing columns, finds out rows that can be grouped together,
+#' and make them multirow cells. Note that if you want to use `column_spec` to
+#' specify column styles, you should use `column_spec` before `collapse_rows`.
+#'
+#' @param kable_input Output of `knitr::kable()` with `format` specified
+#' @param columns Numeric column positions where rows need to be collapsed.
+#'
#' @export
collapse_rows <- function(kable_input, columns = NULL) {
# if (is.null(columns)) {