[SPARK-20020][SPARKR][FOLLOWUP] DataFrame checkpoint API fix version tag

## What changes were proposed in this pull request?

doc only change

## How was this patch tested?

manual

Author: Felix Cheung <felixcheung_m@hotmail.com>

Closes #17356 from felixcheung/rdfcheckpoint2.

R/pkg/R/context.R

@@ -424,7 +424,7 @@ setLogLevel <- function(level) {
 #'\dontrun{
 #' setCheckpointDir("/checkpoint")
 #'}
-#' @note setCheckpointDir since 2.0.0
+#' @note setCheckpointDir since 2.2.0
 setCheckpointDir <- function(directory) {
   sc <- getSparkContext()
   invisible(callJMethod(sc, "setCheckpointDir", suppressWarnings(normalizePath(directory))))