docs: keep README as a landing page, not a second manual

The README is symlinked into the published docs as the site home page, yet
it had grown into a full package-manager and configuration guide. That
duplicated MkDocs content, made updates easy to miss in one place or the
other, and buried the quick path for new readers on GitHub and in the docs.
Split depth into the existing user guides so each audience gets one clear
entry point and the detailed material lives where it can evolve on its own.

Added admonition for visually rich notes and warnings in docs. Added
pymdownx.quotes so GitHub-style callouts render as MkDocs admonitions.

Co-authored-by: Cursor <cursoragent@cursor.com>
Assisted-by: Claude
Signed-off-by: Jakub Nekvinda <jnekvind@redhat.com>

Author: 2 people