h.add-new-event: fix typo and make things clear
+ event: 2013.06: new git training
news: New git training class (vote to join)

We will have another git trainging class. Event details can be
found at http://theslinux.org/events/2013/06-git-training/ .

Please use the Doodle link to select the best time for you.
For more information, please contact luffy{at}theslinux.org
and/or contact us on the mailing lists
Fix typo in news page
h.add-new-event: add notes about /events/

Some big events require a dedicated page in /events/,
while every event requires an entry in /news/