Add missing markup to has filters docs.

docs/Filter/HasChild.md

@@ -7,6 +7,7 @@ and results in parent documents that have child docs matching the query.
 
 ## Simple example
 
+```JSON
 {
     "has_child" : {
         "type" : "blog_tag",

docs/Filter/HasParent.md

@@ -8,6 +8,7 @@ This filter returns child documents which associated parents have matched.
 
 ## Simple example
 
+```JSON
 {
     "has_child" : {
         "type" : "blog_tag",