work-around for roxygen2 breaking change wrt inheritParams

We can no longer inherit a subset of joint documented parameters.

R/substr2.R

@@ -151,14 +151,15 @@
 #' @note Non-ASCII strings are converted to and returned in UTF-8 encoding.
 #'   Width calculations will not work properly in R < 3.2.2.
 #' @note If `stop` < `start`, the return value is always an empty string.
-#' @inheritParams base::substr
 #' @export
 #' @seealso [`?fansi`][fansi] for details on how _Control Sequences_ are
 #'   interpreted, particularly if you are getting unexpected results,
 #'   [`normalize_state`] for more details on what the `normalize` parameter does,
 #'   [`state_at_end`] to compute active state at the end of strings,
 #'   [`close_state`] to compute the sequence required to close active state.
 #' @param x a character vector or object that can be coerced to such.
+#' @param start integer.  The first element to be extracted or replaced.
+#' @param stop integer.  The first element to be extracted or replaced.
 #' @param type character(1L) partial matching
 #'   `c("chars", "width", "graphemes")`, although types other than "chars" only
 #'   work correctly with R >= 3.2.2.  See [`?nchar`][base::nchar].