docs: add missing mjpegScreenshotUrl in capabilities.md (#2462)

* docs: add missing mjpegScreenshotUrl in capabilities.md

* Update capabilities.md

docs/reference/capabilities.md

@@ -80,6 +80,7 @@ about capabilities, refer to the [Appium documentation](https://appium.io/docs/e
 |`appium:simpleIsVisibleCheck`|Use native methods for determining visibility of elements. In some cases this takes a long time. Setting this capability to `false` will cause the system to use the position and size of elements to make sure they are visible on the screen. This can, however, lead to false results in some situations. Defaults to `false`. | `true`, `false`|
 | **Deprecated** `appium:waitForQuiescence`| It allows to turn on/off waiting for application quiescence in `WebDriverAgent`, while performing queries. The default value is `true`. You can avoid [this kind of issues](https://github.com/appium/appium/issues/11132) if you turn it off. Consider using `waitForIdleTimeout` capability instead for this purpose since Appium 1.20.0 | `false` |
 |`appium:mjpegServerPort`|The port number on which WDA broadcasts screenshots stream encoded into MJPEG format from the device under test. It might be necessary to change this value if the default port is busy because of other tests running in parallel. Default value: `9100`|`12000`|
+|`appium:mjpegScreenshotUrl` | The URL of a service that provides realtime device screenshots in MJPEG format. If provided then the actual command to retrieve a screenshot will be requesting pictures from this service rather than directly from the server. Appium does not handle port forward etc to the URL. | `http://<ip address to the device>:9100` |
 |`appium:screenshotQuality`| Changes the initial quality of display screenshots. This capability affects the screenshoting speed and the actual quality of resulting screenshots. Before version 5.4.0 of WebDriverAgent possible values were: `0`, `1` (default), `2`, where `0` abbreviates lossless PNG, `1` is a high-quality JPEG and `2` is a low-quality JPEG. In the version 5.4.0 one more mode has been added (`3`), which is now the default one. It abbreviates lossless HEIC with fallback to PNG if the device does not support hardware-accelerated HEIC encoding. You can also change the value of screenshotQuality in [settings](settings.md). | `2` |
 |`appium:autoAcceptAlerts`| Accept all iOS alerts automatically if they pop up. This includes privacy access permission alerts (location, contacts, photos). Default is `false`. |`true` or `false`|
 |`appium:autoDismissAlerts`| Dismiss all iOS alerts automatically if they pop up. This includes privacy access permission alerts (location, contacts, photos). Default is `false`. |`true` or `false`|