doc: update 2nd lecture slides

lectures/revealjs/02-git-plus-plus.adoc

@@ -29,9 +29,9 @@ IT1901 Fall 2021 - {LECTURE_NO}
 == Groups
 
 - fill the form to be assigned to a group
-- https://s.ntnu.no/it1901groups
-- deadline: Fredag, 27. august 19:00
-- will announce the groups on next Wednesday (September 1st)
+- https://s.ntnu.no/it1901-groups
+- deadline: Mandag, 29. august 17:00
+- will announce the groups on Mandag 5. september 
 
 == Referansegruppe
 
@@ -44,10 +44,10 @@ IT1901 Fall 2021 - {LECTURE_NO}
 
 == Approaching Deadlines
 
-- Friday 27th of August by 19:00
+- Mandag, 29. august 23:59
 ** Fill the group form
 
-- Friday 10th of September by 16:00 
+- Torsdag 8. september / 23:59 
 ** 1st individual deliverable 
 ** group contract