[RM, RAs] Harmonisation of VNF & CNF in CNTT

[rabi-abdel]

More work is still needed beyond what was done in: #1328

Raised by @ulikleber

[ulikleber]

Thanks, Rabi.
We need to bring back the explanation of a cloud native VNF, which should be the typical case, since it allows service provider to deploy cloud native network functions as part of a NFV NS. This needs to be possible with RA2.

Harmonization cannot be done by creating separate sets of terminology for containers and VMs, but by finding commonalities.

[CsatariGergely]

We should use terminology from the normative documents of ETSI NFV IFA, like IFA-040.

[CsatariGergely]

@walterkozlowski works on RM Ch03.

[walterkozlowski]

Updates to RM during the cleanup for Baraque and handover to GSMA NG have taken care of this issue. Any specific issues can still be made and resolved in seperate PRs.