added test case for the json to xml conversion

Author: LindaWang7

json_to_xml/test-input.json

@@ -0,0 +1,8 @@
+{
+    "note": {
+        "to": "John",
+        "from": "Jane",
+        "heading": "Reminder",
+        "body": "Don't forget the meeting at 3 PM!"
+    }
+}