Add information for the exam preparation Q&A sessions

README.md

@@ -19,6 +19,10 @@ The course will take place in a **full online** format:
     member Z(r)ooms. Simply join one, or choose the team member you
     want to discuss with.
 
+  * **Exam preparation**: There will be several online Q&A sessions starting on
+    January 15. The dates and times can be found
+    [here](http://www.sam.math.ethz.ch/~karoger/pt/hs2020/).
+
 **Should you have any issues with the "new" online format, please
  contact us through the mailing list (see [below](#questions)).**