[DOC][SQL] update out-of-date code snippets using SQLContext in all documents.

## What changes were proposed in this pull request?

I search the whole documents directory using SQLContext, and update the following places:

- docs/configuration.md, sparkR code snippets.
- docs/streaming-programming-guide.md, several example code.

## How was this patch tested?

N/A

Author: WeichenXu <WeichenXu123@outlook.com>

Closes #14025 from WeichenXu123/WIP_SQLContext_update.

1 files changed, 2 insertions, 2 deletions

diff --git a/docs/configuration.md b/docs/configuration.md
index cee59cf2aa..1e95b86244 100644
--- a/docs/configuration.md
+++ b/docs/configuration.md
@@ -1564,8 +1564,8 @@ spark.sql("SET -v").show(n=200, truncate=False)
 <div data-lang="r"  markdown="1">
 
 {% highlight r %}
-# sqlContext is an existing sqlContext.
-properties <- sql(sqlContext, "SET -v")
+sparkR.session()
+properties <- sql("SET -v")
 showDF(properties, numRows = 200, truncate = FALSE)
 {% endhighlight %}