Revert "revise Alternative field to Synonym or Similar Terms"

This reverts commit 61d94fa.

R/Catch.R

@@ -8,7 +8,7 @@
 #' \item{Rationale}{Landings and catch are sometimes thought to be
 #' interchangeable but they are not given that catch can also include
 #' bycatch or unwanted catch.}
-#' \item{Synonym or Similar Terms}{total mortality, harvest, total removals}
+#' \item{Alternatives}{total mortality, harvest, total removals}
 #' \item{Range of possible values}{0--Inf}
 #' \item{Units}{mt, numbers}
 #' }