adding in docker .env.example file

docker/.env.example

@@ -412,6 +412,8 @@ SUPABASE_URL=your-server-url
 # The type of vector store to use.
 # Supported values are `weaviate`, `qdrant`, `milvus`, `myscale`, `relyt`, `pgvector`, `pgvecto-rs`, `chroma`, `opensearch`, `oracle`, `tencent`, `elasticsearch`, `elasticsearch-ja`, `analyticdb`, `couchbase`, `vikingdb`, `oceanbase`, `opengauss`, `tablestore`,`vastbase`,`tidb`,`tidb_on_qdrant`,`baidu`,`lindorm`,`huawei_cloud`,`upstash`, `matrixone`.
 VECTOR_STORE=weaviate
+# Prefix used to create collection name in vector database
+VECTOR_INDEX_NAME_PREFIX=Vector_index
 
 # The Weaviate endpoint URL. Only available when VECTOR_STORE is `weaviate`.
 WEAVIATE_ENDPOINT=http://weaviate:8080