Weekend Update anchors Colin Jost and Michael Che have been named co-head writers of NBC's venerable late night series Saturday Night Live. They will join current head writers Kent Sublette and Bryan Tucker. The duo’s appointment brings the number of SNL co-head writers back to four. They fill the void left by the departure of former co-head writers Chris Kelly and Sarah Schneider who left at the beginning of the season to segue to their Comedy Central series executive…