We also change the sporadic use of # optional: FEATURE by the more common # optional - FEATURE.

Depends on #32866
Depends on #32174

CC: @seblabbe @saraedum @kwankyu @slel

Component: documentation

Author: Matthias Koeppe

Branch/Commit: 547206c

Reviewer: Sébastien Labbé

Issue created by migration from https://trac.sagemath.org/ticket/32925