doc: explaing reason for using V0

Author: Devdutt Shenoi

src/handlers/http/ingest.rs

@@ -84,6 +84,7 @@ pub async fn ingest_internal_stream(stream_name: String, body: Bytes) -> Result<
             tags: String::default(),
             metadata: String::default(),
         };
+        // For internal streams, use old schema
         event.into_recordbatch(&schema, None, None, SchemaVersion::V0)?
     };
     event::Event {