[Branch-1.3] [DOC] doc fix for date

Trivial fix.

Author: Daoyuan Wang <daoyuan.wang@intel.com>

Closes #4400 from adrian-wang/docdate and squashes the following commits:

31bbe40 [Daoyuan Wang] doc fix for date

docs/sql-programming-guide.md

@@ -1108,7 +1108,7 @@ in Hive deployments.
   have the same input format.
 * Non-equi outer join: For the uncommon use case of using outer joins with non-equi join conditions
   (e.g. condition "`key < 10`"), Spark SQL will output wrong result for the `NULL` tuple.
-* `UNION` type and `DATE` type
+* `UNION` type
 * Unique join
 * Single query multi insert
 * Column statistics collecting: Spark SQL does not piggyback scans to collect column statistics at