Update README for stability test

README.md

@@ -25,6 +25,7 @@ Works with mobile versions too.
 * Telemetry (optional)
 * Results sharing (optional)
 * Multiple Points of Test (optional)
+* Connection stability test with latency charting, loss tracking, threshold alerts, and CSV export
 
 ![Screenrecording of a running Speedtest](https://speedtest.fdossena.com/mpot_v7.gif)
 
@@ -40,7 +41,7 @@ Works with mobile versions too.
 Assuming you have PHP and a web server installed, the installation steps are quite simple.
 
 1. Download the source code and extract it
-1. Copy the project files to your web server's shared folder (ie. `/var/www/html/speedtest` for Apache). For the current layout, the web root should contain `index.html`, `index-classic.html`, `index-modern.html`, `design-switch.js`, `config.json`, `speedtest.js`, `speedtest_worker.js`, `favicon.ico`, and the `backend` folder.
+1. Copy the project files to your web server's shared folder (ie. `/var/www/html/speedtest` for Apache). For the current layout, the web root should contain `index.html`, `index-classic.html`, `index-modern.html`, `stability.html`, `design-switch.js`, `config.json`, `speedtest.js`, `speedtest_worker.js`, `stability_worker.js`, `favicon.ico`, and the `backend` folder.
 1. Also copy the contents of `frontend/` into the same web root so the modern UI assets end up in `styling/`, `javascript/`, `images/`, and `fonts/` next to the HTML files.
 1. Optionally, copy the results folder too, and set up the database using the config file in it.
 1. Be sure your permissions allow read and execute access where needed.
@@ -72,6 +73,12 @@ If you want to contribute or develop with LibreSpeed, see [DEVELOPMENT.md](DEVEL
 
 LibreSpeed supports both the classic and modern UI. The root `index.html` acts as a lightweight switcher and redirects to `index-classic.html` or `index-modern.html` based on `config.json` (`useNewDesign`) or URL overrides (`?design=new` / `?design=old`). For architecture and deployment details (including Docker behavior), see [DESIGN_SWITCH.md](DESIGN_SWITCH.md).
 
+## Stability test
+
+LibreSpeed includes a standalone connection stability test at `stability.html`, linked from both the classic and modern interfaces. It repeatedly measures ping over a selected duration and reports current, average, minimum, maximum, jitter, and failed request percentage values with a live chart.
+
+The stability test can target the local LibreSpeed backend, one of the configured multiple points of test, or built-in external targets such as Google, Cloudflare, and Apple. It also supports optional latency threshold alerts and CSV export of the collected samples. Docker deployments copy `stability.html` and `stability_worker.js` into the web root and reuse the same server list configuration as the main UI.
+
 ## Docker
 
 A docker image is available on [GitHub](https://github.com/librespeed/speedtest/pkgs/container/speedtest), check our [docker documentation](doc_docker.md) for more info about it.