Rearchitect local package building documentation
To make contribution easy to contributors and other teams in GitLab.
- I deleted stuff that I don't think anyone ever uses.
- Consolidated stuff to a single page.
Note: It might be easier to check http://docs-preview-omnibus-update-package-build-docs.178.62.207.141.nip.io/omnibus/build/README.html and see what is missing.
Edited by Balasankar 'Balu' C