(docs): Restructure ROS 2 tutorials & fix dead / unclear setup links

[anakafeel]

Is your feature request related to a problem? Please describe.

The current ROS 2 tutorials and setup pages are not very clear for new contributors and contain multiple dead or outdated links.
Right now it’s hard to tell:

• What the correct learning order is
• Which links are still valid / official
• What is required vs optional for contributors

This makes onboarding into the robotics stack confusing, especially for beginners.

Describe the solution you'd like

Restructure the ROS 2 section into a clearer, more guided learning path, for example:

1. A single ROS 2 Overview / Entry Point page:

   • What ROS 2 is
   • Why we use it in ARC
   • Which distro we target (e.g. Humble, Iron, etc.)

2. A clean Setup Guide:

   • Verified working links only
   • Explicit platform support (Linux / WSL / native)
   • Minimal required steps for contributors

3. Reworked Labs / Tutorials:

   • Ordered progression (Basics → Packages → Nodes → Topics → Launch → etc.)
   • Each lab with:
     • Clear objective
     • Expected outcome
     • No dead links
     • Working commands

4. A final “What you should know to contribute” page:

   • ROS concepts actually used in the car
   • Links to relevant ARC repos/packages

Describe alternatives you've considered

• Leaving existing structure and just fixing links (but the overall flow is still confusing)
• Linking directly to external ROS docs only (but ARC-specific context is still needed)

Additional context

This is mainly about improving onboarding and reducing friction for new robotics contributors.
Right now the ROS section feels fragmented and outdated, which makes it harder to bring new people into the car stack.