update stdout db engine output example

pkg/README.md

@@ -15,5 +15,10 @@ program to build your own pipelines on the fly!
 **Example Output**
 
 ```json
-
+{"infoHash":"f84b51f0d2c3455ab5dabb6643b4340234cd036e","name":"Big_Buck_Bunny_1080p_surround_frostclick.com_frostwire.com","files":[{"size":928670754,"path":"Big_Buck_Bunny_1080p_surround_FrostWire.com.avi"},{"size":5008,"path":"PROMOTE_YOUR_CONTENT_ON_FROSTWIRE_01_06_09.txt"},{"size":3456234,"path":"Pressrelease_BickBuckBunny_premiere.pdf"},{"size":180,"path":"license.txt"}]}
 ```
+
+> **WARNING:**
+>
+> Please beware that the schema of the object (dictionary) might change in backwards-incompatible ways 
+> in the future; although I'll my best to ensure it won't happen.