Adjust docs banner to indicate that Py 2 is EOL
<aside id="python27eol">
<a href="https://pythonclock.org/" target="_blank" title="Python 2.7 EOL Countdown">
Python 3, the new best practice, is here to stay.
- Python 2 will retire in only <time></time>!
+ Python 2 has retired <time></time> ago!
</a>
<p>
Since version 18.0.0 CherryPy has
