Add migration note, fix new (?) doc error

Author: srowen

R/pkg/R/SQLContext.R

@@ -388,6 +388,7 @@ read.orc <- function(path, ...) {
 #' Loads a Parquet file, returning the result as a SparkDataFrame.
 #'
 #' @param path path of file to read. A vector of multiple paths is allowed.
+#' @param ... additional external data source specific named properties.
 #' @return SparkDataFrame
 #' @rdname read.parquet
 #' @name read.parquet

docs/sparkr.md

@@ -667,8 +667,12 @@ You can inspect the search path in R with [`search()`](https://stat.ethz.ch/R-ma
 
 ## Upgrading to SparkR 2.3.1 and above
 
- - In SparkR 2.3.0 and earlier, the `start` parameter of `substr` method was wrongly subtracted by one and considered as 0-based. This can lead to inconsistent substring results and also does not match with the behaviour with `substr` in R. In version 2.3.1 and later, it has been fixed so the `start` parameter of `substr` method is now 1-base. As an example, `substr(lit('abcdef'), 2, 4))` would result to `abc` in SparkR 2.3.0, and the result would be `bcd` in SparkR 2.3.1.
+ - In SparkR 2.3.0 and earlier, the `start` parameter of `substr` method was wrongly subtracted by one and considered as 0-based. This can lead to inconsistent substring results and also does not match with the behaviour with `substr` in R. In version 2.3.1 and later, it has been fixed so the `start` parameter of `substr` method is now 1-based. As an example, `substr(lit('abcdef'), 2, 4))` would result to `abc` in SparkR 2.3.0, and the result would be `bcd` in SparkR 2.3.1.
 
 ## Upgrading to SparkR 2.4.0
 
  - Previously, we don't check the validity of the size of the last layer in `spark.mlp`. For example, if the training data only has two labels, a `layers` param like `c(1, 3)` doesn't cause an error previously, now it does.
+
+## Upgrading to SparkR 3.0.0
+
+ - The deprecated methods `parquetFile`, `jsonRDD` and `jsonFile` in `SQLContext` have been removed. Use `read.parquet` and `read.json`.