Remove doc of health check (#12363)

### What problem does this PR solve?

System web page is disabled since v0.22.0, and the health check API is
also described in API reference. This document is obsolete.

### Type of change

- [x] Documentation Update

Signed-off-by: Jin Hai <haijin.chn@gmail.com>

docs/guides/run_health_check.md

@@ -1,109 +0,0 @@
----
-sidebar_position: 8
-slug: /run_health_check
----
-
-# Monitoring
-
-Double-check the health status of RAGFlow's dependencies.
-
----
-
-The operation of RAGFlow depends on four services:
-
-- **Elasticsearch** (default) or [Infinity](https://github.com/infiniflow/infinity) as the document engine
-- **MySQL**
-- **Redis**
-- **MinIO** for object storage
-
-If an exception or error occurs related to any of the above services, such as `Exception: Can't connect to ES cluster`, refer to this document to check their health status.
-
-You can also click you avatar in the top right corner of the page **>** System to view the visualized health status of RAGFlow's core services. The following screenshot shows that all services are 'green' (running healthily). The task executor displays the *cumulative* number of completed and failed document parsing tasks from the past 30 minutes:
-
-![system_status_page](https://github.com/user-attachments/assets/b0c1a11e-93e3-4947-b17a-1bfb4cdab6e4)
-
-Services with a yellow or red light are not running properly. The following is a screenshot of the system page after running `docker stop ragflow-es-10`:
-
-![es_failed](https://github.com/user-attachments/assets/06056540-49f5-48bf-9cc9-a7086bc75790)
-
-You can click on a specific 30-second time interval to view the details of completed and failed tasks:
-
-![done_tasks](https://github.com/user-attachments/assets/49b25ec4-03af-48cf-b2e5-c892f6eaa261)
-
-![done_vs_failed](https://github.com/user-attachments/assets/eaa928d0-a31c-4072-adea-046091e04599)
-
-## API Health Check
-
-In addition to checking the system dependencies from the **avatar > System** page in the UI, you can directly query the backend health check endpoint:
-
-```bash
-http://IP_OF_YOUR_MACHINE/v1/system/healthz
-```
-
-Here `<port>` refers to the actual port of your backend service (e.g., `7897`, `9222`, etc.).
-
-Key points:
-- **No login required** (no `@login_required` decorator)
-- Returns results in JSON format
-- If all dependencies are healthy → HTTP **200 OK**
-- If any dependency fails → HTTP **500 Internal Server Error**
-
-### Example 1: All services healthy (HTTP 200)
-
-```bash
-http://127.0.0.1/v1/system/healthz
-```
-
-Response:
-
-```http
-HTTP/1.1 200 OK
-Content-Type: application/json
-Content-Length: 120
-
-```
-
-Explanation:
-- Database (MySQL/Postgres), Redis, document engine (Elasticsearch/Infinity), and object storage (MinIO) are all healthy.
-- The `status` field returns `"ok"`.
-
-### Example 2: One service unhealthy (HTTP 500)
-
-For example, if Redis is down:
-
-Response:
-
-```http
-HTTP/1.1 500 INTERNAL SERVER ERROR
-Content-Type: application/json
-Content-Length: 300
-
-```
-
-Explanation:
-- `redis` is marked as `"nok"`, with detailed error info under `_meta.redis.error`.
-- The overall `status` is `"nok"`, so the endpoint returns 500.
-
----
-
-This endpoint allows you to monitor RAGFlow’s core dependencies programmatically in scripts or external monitoring systems, without relying on the frontend UI.
-  "redis": "nok",
-  "doc_engine": "ok",
-  "storage": "ok",
-  "status": "nok",
-  "_meta": {
-    "redis": {
-      "elapsed": "5.2",
-      "error": "Lost connection!"
-    }
-  }
-}
-```
-
-Explanation:
-- `redis` is marked as `"nok"`, with detailed error info under `_meta.redis.error`.
-- The overall `status` is `"nok"`, so the endpoint returns 500.
-
----
-
-This endpoint allows you to monitor RAGFlow’s core dependencies programmatically in scripts or external monitoring systems, without relying on the frontend UI.