5.1.1. Introduction:* adding PNF requirements 

The requirement to support to PNF onboarding on Dublin release, need to add PNF related requriement.

Proposed change:

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5.1.1. Introduction

The following sub-clauses describe the numbered requirements for VNF Descriptor (VNFD) and PNF Descriptor (PNFD) or in other words the VNF/PNF Service Template based on the most updated draft of ETSI NFV-SOL001 standard for VNF/PNF Descriptor. The ETSI standard specifies a NFV specific data model using TOSCA/YAML data model constructs specified in TOSCA Simple Profile in YAML v.1.2.

The requirements for TOSCA/CSAR based VNF/PNF package are described as well and they are based on ETSI NFV-SOL004 standard.

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