[Minor] fix typo in SQL document

Author: CodingCat <zhunansjtu@gmail.com>

Closes #4656 from CodingCat/fix_typo and squashes the following commits:

b41d15c [CodingCat] recover
689fe46 [CodingCat] fix typo

docs/sql-programming-guide.md

@@ -159,7 +159,7 @@ you to construct DataFrames when the columns and their types are not known until
 
 <div data-lang="scala"  markdown="1">
 
-The Scala interaface for Spark SQL supports automatically converting an RDD containing case classes
+The Scala interface for Spark SQL supports automatically converting an RDD containing case classes
 to a DataFrame.  The case class
 defines the schema of the table.  The names of the arguments to the case class are read using
 reflection and become the names of the columns. Case classes can also be nested or contain complex