[CentOS-docs] Remove cancelled timeslots from "Past Office Hours" section on "OfficeHours" page

[Timothy Lee]

Dear all,

In order to reduce clutter, may I suggest that cancelled timeslots be 
removed from the "Past Office Hours" section of the "OfficeHours" wiki page?

Also, I noticed that the URL for 20th Jan 2014 event is missing.

Regards,
Timothy Lee