Incomplete ISO 3166-1 Flag Conformance

[vapidinfinity]

I've noticed that this repository under- (and over-) conforms to the ISO 3166-1 alpha-2 standard.

Countries like Yugoslavia (YU), and the Soviet Union (SU) are present, which overconform ISO 3166-1 due to their nonexistence and lead into ISO 3166-3.

Additionally, the following flags aren't present that exist as part of ISO 3166-1:
• BV: Bouvet Island
• EH: Western Sahara
• GS: South Georgia and the South Sandwich Islands
• HM: Heard Island and McDonald Islands
• IO: British Indian Ocean Territory
• SJ: Svalbard and Jan Mayen
• UM: United States Minor Outlying Islands

Please add these flags.
Thanks heaps!!