Add an example of including sql from docs

Original commit: elastic/x-pack-elasticsearch@aa4ad288dc

docs/en/sql/index.asciidoc

@@ -2,6 +2,8 @@
 [[xpack-sql]]
 = SQL Access
 
+:jdbc-tests: {docdir}/../../sql/jdbc/src/test/resources
+
 [partintro]
 --
 Overview
@@ -12,3 +14,5 @@ include::sql-query-dsl.asciidoc[]
 include::sql-rest.asciidoc[]
 include::sql-jdbc.asciidoc[]
 include::sql-cli.asciidoc[]
+
+:jdbc-tests!:

docs/en/sql/sql-query-dsl.asciidoc

@@ -3,3 +3,11 @@
 == SQL Query DSL
 
 Content
+
+Example!
+
+
+["source","sql",subs="attributes,callouts,macros"]
+--------------------------------------------------
+include-tagged::{jdbc-tests}/select.sql-spec[wildcardWithOrder]
+--------------------------------------------------

sql/jdbc/src/test/resources/select.sql-spec

@@ -3,7 +3,9 @@
 //
 
 wildcardWithOrder
-SELECT * FROM "test_emp" ORDER BY emp_no;
+// tag::wildcardWithOrder
+SELECT * FROM test_emp ORDER BY emp_no;
+// end::wildcardWithOrder
 column
 SELECT last_name FROM "test_emp" ORDER BY emp_no;
 columnWithAlias