Update hakes-worker README

Author: hugy718

docker/hakes-worker/no-sgx/README.md

@@ -6,6 +6,25 @@
 docker build -t hakes-hakesworker-nosgx:v1 -f docker/hakes-worker/no-sgx/Dockerfile .
 ```
 
+## prepare the config file
+
+The config file mounted for hakes-worker container controls how it interacts with other components in HAKES to serve user requests. A sample config is show below.
+
+```json
+{
+  "embed_endpoint_type": "hakes-embed",
+  "embed_endpoint_config": "",
+  "embed_endpoint_addr": "10.10.10.28:2700",
+  "search_worker_addrs": ["10.10.10.57:2800"],
+  "preferred_search_worker": 0,
+  "store_addr": "10.10.10.26:2600"
+}
+```
+
+* `embed_endpoint_type`, `embed_endpoint_config` and `embed_endpoint_addr` dictate the embed service that converts raw data in user requests to embedding vectors. When the `embed_endpoint_type` is `hakes-embed`, it uses an embed-worker server or function. We also support external embedding services through the [embed-endpoint](../../../embed-endpoint/) module, such as `openai` and `huggingface` for open-ai embedding APIs and huggingface inrference endpoints.
+* `search_worker_addrs` points to the search-workers that maintains the vector index and `preferred_search_worker` indicates the request routing to a specific search-worker that the hakes-worker will contact.
+* `store_addr` points to the hakes-store service that persists the data.
+
 ## run
 
 ```sh