Create a single source of documentation for the trento project

[EMaksy]

Purpose of this PR (WIP)

This PR aims to lay the foundation for a unified documentation repository that combines both user-facing and developer documentation for the Trento project.
The docs repository will be the source for the upcoming single documentation page

About the directory structure:
components: All the upstream projecs docs like web and wanda
dev_docs: All developer focused documentation like adr architecture coding standarts and so on
trento_suse: All documantation which is published at suse.com

docs/
├── components/     # Upstream project docs (e.g., web, wanda)
├── dev_docs/       # Developer-focused docs (ADRs, architecture, coding standards)
├── trento_suse/    # User-facing docs published on suse.com
├── dev_docs_legacy/ # Legacy docs (temporary, pending review & cleanup)
├──  templates/ # Contains templates like badges and guides.
└── modules/ # Contains antora modules with navigation files for the antora page

Important notes

• All documentation meant to be published on the documentation site must:
• Be written in Asciidoc (.adoc)
• Be placed in the correct directory
• Have the corresponding module's nav.adoc file updated (see README.md for guidance)
• Documentation not intended for the public developer docs (e.g., notes, internal guides) can remain in Markdown or other formats and does not need to follow Antora conventions.

This PR includes multiple steps:

• Add CI validation for user-facing SUSE docs
• Update license year
• Update README.md with instructions for Antora setup and usage
• Add Antora site build cookbook and navigation modules (antora.yml)
• Restructure the repo:
  • Move converted .adoc content into dev_docs
  • Fetch and convert upstream docs into components
• fetched upstream project docs to components directory and convert them to adoc
• Preserve old docs under dev_docs_legacy/ (to be cleaned up after discussions)