feat(Valdium): Launch docs

[ilitteri]

What ❔

Adds a launch guide for running the system in Validium mode

Why ❔

To have a guide for developers for being able to run the system in Validiu mode

Checklist

• [x] PR title corresponds to the body of PR (we generate changelog entries from PRs).
• [ ] Tests for the changes have been added / updated.
• [x] Documentation comments have been added / updated.
• [ ] Code has been formatted via zk fmt and zk lint.
• [ ] Spellcheck has been run via zk spellcheck.
• [ ] Linkcheck has been run via zk linkcheck.