Update value overrides to match RAGFlow v0.21.1 chart

Author: sd109

helm-azimuth/values.yaml

@@ -7,12 +7,20 @@ zenithClient:
   skipAuth: false
 
 
-# RAGflow values
+# Config overrides for the underlying RAGFlow chart
 ragflow:
+  # RAGFlow container config
+  ragflow:
+    image:
+      # Use a non-slim image which includes embedding models
+      # NOTE(scott): Maybe we can remove this once we are using
+      # the HU-hosted embedding and reranking models in RAGFlow?
+      tag: v0.21.1
+  # Elasticsearch seems more stable than other options for now
   env:
-    RAGFLOW_IMAGE: infiniflow/ragflow:v0.19.1
     DOC_ENGINE: elasticsearch
 
+  # Clean up redis volumes when Azimuth app is uninstalled
   redis:
     persistence:
       retentionPolicy: