[BUG] Integrator certification missing in docs

[toothstone]

A company interested in getting SCS-IaaS Integrator certified has made me aware that there is no mention of that kind of certification at https://docs.scs.community/standards/certification/overview/ and sub-pages, especially neither at "Scopes and versions"

This feels like quite an oversight, there should at least be some mention of SCS-0007.

[fkr]

Thanks @toothstone - indeed, we should add it there.

[fkr]

@toothstone I've opened SovereignCloudStack/docs#354