[SPARK-19396][DOC] JDBC Options are Case In-sensitive

### What changes were proposed in this pull request?
The case are not sensitive in JDBC options, after the PR apache#15884 is merged to Spark 2.1.

### How was this patch tested?
N/A

Author: gatorsmile <[email protected]>

Closes apache#16734 from gatorsmile/fixDocCaseInsensitive.

Author: gatorsmile

docs/sql-programming-guide.md

@@ -1135,7 +1135,7 @@ Tables from the remote database can be loaded as a DataFrame or Spark SQL tempor
 the Data Sources API. Users can specify the JDBC connection properties in the data source options.
 <code>user</code> and <code>password</code> are normally provided as connection properties for
 logging into the data sources. In addition to the connection properties, Spark also supports
-the following case-sensitive options:
+the following case-insensitive options:
 
 <table class="table">
   <tr><th>Property Name</th><th>Meaning</th></tr>