Draft: docs: simplify GitLab package installation process
Relates to issue #570513 (closed)
This MR was created by Duo in Session 1127604
Changes
- Simplify initial password creation documentation for Linux package installation
- Reorganize installation steps with clearer progression and logical flow
- Add dedicated "Initial sign-in" section with explicit login instructions
- Move advanced configuration options to separate section to keep basic installation simple
- Address user feedback about vague password procedures and login confusion