address comments

Author: Wayne Zhang

R/pkg/vignettes/sparkr-vignettes.Rmd

@@ -405,7 +405,7 @@ result <- gapply(
 head(arrange(result, "max_mpg", decreasing = TRUE))
 ```
 
-Like gapply, `gapplyCollect` applies a function to each partition of a `SparkDataFrame` and collect the result back to R `data.frame`. The output of the function should be a `data.frame` but no schema is required in this case. Note that `gapplyCollect` can fail if the output of the UDF on all partitions cannot be pulled into the driver's memory.
+Like `gapply`, `gapplyCollect` can apply a function to each partition of a `SparkDataFrame` and collect the result back to R `data.frame`. The output of the function should be a `data.frame` but no schema is required in this case. Note that `gapplyCollect` can fail if the output of the UDF on all partitions cannot be pulled into the driver's memory.
 
 ```{r}
 result <- gapplyCollect(