Add beginner-friendly first-time setup guide

[MargusG]

What this PR does

Adds a beginner-first “First Time Setup” guide focused on reducing confusion and early drop-off during initial use of Open WebUI.

The guide is written for non-technical users and:

• avoids jargon where possible
• defines clear success checkpoints
• explains common points of confusion without blaming the user
• includes a simple, verifiable document test flow
• documents real first-run UI friction (upload delay, silent indexing)

Why this is needed

New users often struggle to reach first success due to:

• not knowing whether the system is working
• uncertainty around model selection
• silent or slow document ingestion
• difficulty finding Knowledge-related UI actions

This guide is designed to shorten “time-to-first-success” and reduce early abandonment.

Scope

• Documentation only
• No behavioral or UI changes
• Beginner-focused, not a replacement for advanced docs

Target audience

• First-time users
• Non-technical users
• Self-hosted users evaluating Open WebUI for the first time

Feedback welcome — especially on wording, structure, and placement.

[pr-validator-bot]

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[Classic298]

Thanks for your contribution. If you attempted to add this to the tutorials section I would probably have approved this PR, but since you attempt to add this to getting-started, i am not sure it is wanted there.

@tjbck will have to confirm that here and review the PR and the tutorial

[MargusG]

Thanks for the feedback — that makes sense.

I’m happy to move this guide to the tutorials section if that’s a better fit.
My intention was to help first-time users reach a working setup with minimal friction, not to redefine the getting-started structure.

I’ll wait for @tjbck’s input, and once confirmed I can move the guide to the appropriate tutorials location and update the PR accordingly.