add parameter refresh to mqtt activity for dynamic sleep time override

[elratt0r]

Useful for having a certain activity displayed for a shorter time range or having more frequent updates.
By using the activity/run topic, it only overwrites the sleep duration once, so no need to keep track of setting
the interval up and down manually.

Usage example:
I have an automation for commute times that runs every 5 minutes in the morning between 6 and 9.
After the sensor update I send mqtt.publish({"action": "hass", "refresh": "300"}) to have a shorter update interval
for the next run so the information on the display is more up-to-date.

[lanrat]

This is a great idea! I'll even use it myself. Thanks!

[lanrat]

@elratt0r would you mind providing an example of how to use this to dashboard.md or another doc?