Refactor README to reduce duplication with `bottlerocket.dev/en/brupop/`

**Image I'm using:**
n/a

**Issue or Feature Request:**

Brupop Documentation launched on Feb 14 and there is substantial overlap with the README. To reduce duplication, we should people interested in running Brupop to the docs and focus the readme to contributors and development.

Start with the repository README and compare its Brupop user-facing content with the documentation at bottlerocket.dev/en/brupop/. Identify duplicated material and the sections aimed at users versus contributors or developers. Done means the README directs users to the documentation while retaining relevant contributor and development information.

Written by the indexing model from the issue text.