Digg — Kevin Rose’s reboot of his once-popular link-sharing site — is laying off a sizable portion of its staff, the company announced on Friday. The startup is not closing, however, Digg CEO Justin Mezzell said. Instead, Rose will return to work on Digg full-time as the company tries to find its footing. Rose will continue to work as an advisor at investing firm True Ventures, but will make Digg his primary focus from here on out. The startup had set out to offer an alternative to existing