Fix error in JSON_QUERY_CONVERTER,

add missing setter in CJ_QUERY
Add simple use cases, examples to build CJ from the API.

Author: jvelilla

library/cj_query.e

@@ -62,6 +62,15 @@ feature -- Element Change
 			name_set: name ~ a_name
 		end
 
+
+	set_prompt (a_prompt: STRING)
+		do
+			prompt := a_prompt
+		ensure
+			prompt_set: prompt ~ a_prompt
+		end
+
+
 	add_data (a_data: CJ_DATA)
 		local
 			l_data: like data

library/converter/json_query_converter.e

@@ -42,7 +42,7 @@ feature -- Conversion
 				Result.set_name (l_ucs)
 			end
 			if attached {STRING_32} json.object (j.item (prompt_key), Void) as l_ucs then
-				Result.set_rel (l_ucs)
+				Result.set_prompt (l_ucs)
 			end
 			if attached {JSON_ARRAY} j.item (data_key) as ja then
 				from