The end time is not updated for heartbeat requests (#232)

See matomo-org/matomo#9617

docs/3.x/tracking-api.md

@@ -123,7 +123,7 @@ Learn more in the [Media Analytics HTTP Tracking API Reference](/guides/media-an
 ### Other parameters
 
 * `send_image` — If set to 0 (`send_image=0`) Piwik will respond with a HTTP 204 response code instead of a GIF image. This improves performance and can fix errors if images are not allowed to be obtained directly (eg Chrome Apps). Available since Piwik 2.10.0
-* `ping`  — If set to 1 (`ping=1`), the request will be a [Heartbeat request](https://matomo.org/faq/how-to/faq_21824/) which will not track any new activity (such as a new visit, new action or new goal). The heartbeat request will only update the visit's end time to provide accurate "Visit duration" metric.
+* `ping`  — If set to 1 (`ping=1`), the request will be a [Heartbeat request](https://matomo.org/faq/how-to/faq_21824/) which will not track any new activity (such as a new visit, new action or new goal). The heartbeat request will only update the visit's total time to provide accurate "Visit duration" metric.
 
 ## Tracking Bots