Add Helm chart deployment method (#3815)

### What problem does this PR solve?

Add's a Helm chart for deploying RAGFlow on Kubernetes. 

Closes #864. 

### Type of change

- [X] New Feature (non-breaking change which adds functionality)

helm/templates/elasticsearch-config.yaml

@@ -0,0 +1,13 @@
+{{- if eq .Values.env.DOC_ENGINE "elasticsearch" -}}
+apiVersion: v1
+kind: ConfigMap
+metadata:
+  name: {{ include "ragflow.fullname" . }}-es-config
+data:
+  node.name: "es01"
+  bootstrap.memory_lock: "false"
+  discovery.type: "single-node"
+  xpack.security.enabled: "true"
+  xpack.security.http.ssl.enabled: "false"
+  xpack.security.transport.ssl.enabled: "false"
+{{- end -}}