#28745 updates the installation manual and explains the use of SAGE_ROOT/environment[-optional].yml.

As section in the developer's guide should explain the use of SAGE_ROOT/src/environment-[optional].yml

... from https://wiki.sagemath.org/Conda

including answers to the following questions (from #31099):

• How do I now create a conda environment with a given name in a given location with the sage dependencies installed, and activate this env later and run say the doctests? Similarly, say I've created a conda env myself and activated it.
• How can I now install the sage dependencies and run tests/lints using tox in this env?

Depends on #28745

CC: @dimpase @isuruf @saraedum @tobiasdiez

Component: documentation

Keywords: conda, sd110, sd111

Author: Isuru Fernando, Matthias Koeppe

Branch/Commit: b4e9e8c

Reviewer: Matthias Koeppe, Tobias Diez

Issue created by migration from https://trac.sagemath.org/ticket/28746