Well the only official ones are contained in the rulebooks. The community updated official gangs are available in the NCE (Necromunda Community Edition) and the OCE (Outlanders Community Edition). All the other gangs available in the vault, old or new, are in no way "official".
It all about which ruleset you wish to play, and the various vault resources are tagged appropriately.
ORB - Original Rulebook from 1995
LRB - Living Rulebook from 2001
NCE - Necromunda Community Edition from the last decade of efforts
Most in the 'tribe play NCE, and the YakTribe Necromunda gang and campaign tools default to NCE as well.