Fix: Provide a description of the api_stats.sh script and its usage

Author: mrajagopal

nginx-utils/README.md

@@ -17,7 +17,10 @@ kubectl -n <namespace> debug -it <nic-pod-name> --image=ghcr.io/nginx/nginx-util
 Please refer to the [nginx-utils packages page](https://github.com/nginx/nginx-supportpkg-for-k8s/pkgs/container/nginx-utils) for versions.  
 
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-#### Example usage of `api_stats.sh` found in the container:  
+#### Example usage of `api_stats.sh` found in the container:
+The `api_stats.sh` script is designed to facilitate accessing the [/api](https://nginx.org/en/docs/http/ngx_http_api_module.html#api) endpoint to query various status information, configuring upstream server groups on-the-fly, and managing key-value pairs without the need of reconfiguring nginx.
+
+<font color="red">NOTE</font>: The `api_stats.sh` script requires an `/api` endpoint that is listening on `loopback`, in a given `port`.
 ```
 kubectl -n <namespace> debug -it <nic-pod-name> --image=ghcr.io/nginx/nginx-utils:latest --target=nginx-ingress