[University] Closing university at lists.adacore.com

[Pierre-Marie de Rodat]

Hello,

AdaCore U has been retired, so we are now closing this mailing list.
You can find an archive of all the courses on our YouTube playlist. In 
order to report an issue, please visit 
https://github.com/AdaCoreU/Courses/issues.

Be sure to check out our new interactive learning site learn.adacore.com.

-- 
Pierre-Marie de Rodat