Show date, time (and maybe commit SHA) of last update on interop page(s)

[ulrich-berkmueller]

It would be nice to see the date and time (and maybe also the commit SHA) of the last aligned test run the interop page(s) is/are based on.

Why? You save clicks to see which aligned test run(s) the displayed data is based on. Further you can detect more quickly when something is broken with aligned test runs when date/time was not updated after some days (currently, the lack of a test run of one browser prevents the statistics of all other browsers from being updated).