docs: update speedtest setup instructions for native engine

front/plugins/internet_speedtest/README.md

@@ -6,20 +6,30 @@ A plugin allowing for executing regular internet speed tests.
 
 This plugin supports two engines:
 1.  **Baseline Engine**: Uses the Python `speedtest-cli` library (default).
-2.  **Native Engine (Optimized)**: Uses the native Ookla Speedtest binary.
+2.  **Native Engine (Optimized)**: Uses the official native Ookla Speedtest binary.
 
 #### Opt-in for Native Engine
-To use the native engine:
-- Provide the native `speedtest` binary in your environment: [Speedtest CLI Homepage](https://www.speedtest.net/apps/cli)
-- Map the binary to `/usr/bin/speedtest` in the container.
-- **Ensure the native speedtest binary is installed on the host at the source path.**
+To use the native engine, you must provide the official binary to the container. The native binary is **strongly recommended** for internet connections > 100 Mbps to ensure CPU bottlenecks don't affect your results.
+
+**Setup Instructions:**
+1. **Download:** Get the official binary for your architecture from the [Speedtest CLI Homepage](https://www.speedtest.net/apps/cli).
+2. **Place & Prepare:** Place the binary on your host machine (e.g., in `/opt/netalertx/`) and ensure it has executable permissions:
+
+```bash
+   chmod +x /opt/netalertx/speedtest
+```
+
+3. Docker Mapping: Map the host file to exactly `/usr/bin/speedtest` inside the container via your `docker-compose.yml`:
 
 ```yaml
-volumes:
-  - /usr/bin/speedtest:/usr/bin/speedtest:ro
+services:
+  netalertx:
+    volumes:
+      - /opt/netalertx/speedtest:/usr/bin/speedtest:ro
 ```
--  The plugin will automatically detect and use it for subsequent tests.
 
+### Why this mapping?
+Inside the container, a Python version of speedtest often exists in the virtual environment (`/opt/venv/bin/speedtest`). Mapping your native binary specifically to `/usr/bin/speedtest` allows the plugin to prioritize the high-performance native engine over the baseline library.
 
 ### Data Mapping
 
@@ -30,4 +40,4 @@ volumes:
 ### Notes
 
 - The native binary is recommended for connections > 100 Mbps.
-- If the native binary is not detected, the plugin seamlessly falls back to the baseline library.
+- If the native binary is not detected at /usr/bin/speedtest, or if it fails to execute, the plugin will seamlessly fall back to the baseline Python library.