We add a section to the developer manual, explaining packaging portions of the Sage library to distributions packages.

Related discussion in the sage devel:

https://groups.google.com/g/sage-devel/c/cTifWZOAfH8

See also: #32925 Improve documentation of sage.features

CC: @kwankyu @dimpase @tobiasdiez

Component: documentation

Author: Matthias Koeppe, Kwankyu Lee

Branch/Commit: b555735

Reviewer: Kwankyu Lee, Matthias Koeppe

Issue created by migration from https://trac.sagemath.org/ticket/32899