Update onboarding guideline how to use Design System

[marcelbertram]

Scope

Currently we see that some people struggle in correctly using the Design System as Library in Figma. Also we have some projects and people outside of the Figma ORG (Only DPO ARTs and some marketing projects), where we should better explain how to best use the Design System library and update it.

Notes

• Current Docu: https://designsystem.porsche.com/v3/designing/introduction
• Remove Onboarding Signup (ux.porsche.com) not available anymore
• Workflow (internal & external) should be better explained, currently the library is documented as inspiration
• Better connection with the brandguide in both ways
• Consider public library #50

Acceptance Criteria

• [ ] Onboarding is improved for internal (PAG Figma ORG) and external designers (Own Figma Org or private user)
• [ ] Some user evaluation done