Fixed the year for the 2nd phase deadline.

Author: janpgit

docs/index.html

@@ -174,7 +174,7 @@ <h2><a name="final_assignment">Final Lab Assignment</a></h2>
 
 <p>The second phase must be finished and handed over to us via email before the
 examination period for the Summer semester starts, i.e. by <b>Sunday 23:59, May
-23, 2020, CET</b>.  You need to send the email before the deadline.  The date
+23, 2021, CET</b>.  You need to send the email before the deadline.  The date
 stands even if the semester is prolonged.
 
 <p>The deadlines are hard requirements so stick to the schedule.  We do not