`conda config --describe` default configuration examples for plugin settings don't work in `.condarc` files

Checklist

I added a descriptive title
I searched open reports and couldn't find a duplicate

What happened?

Originally discovered by @dholth

When “conda config --describe” is run, the example for shown for a plugin looks like:

plugins.setting_name: example_value

This can’t it actually be used in a .condarc file because the correct way to define it is:

plugins:
  setting_name: example_value

Conda Info

active environment : None
            shell level : 0
       user config file : /Users/user/.condarc
 populated config files : /Users/user/.condarc
          conda version : 25.9.1
    conda-build version : 25.9.0
         python version : 3.13.5.final.0
                 solver : libmamba (default)
       virtual packages : __archspec=1=m1
                          __conda=25.9.1=0
                          __osx=15.6.1=0
                          __unix=0=0
       base environment : /Users/user/miniconda  (writable)
      conda av data dir : /Users/user/miniconda/etc/conda
  conda av metadata url : None
           channel URLs : https://conda.anaconda.org/conda-forge/osx-arm64
                          https://conda.anaconda.org/conda-forge/noarch
          package cache : /Users/user/miniconda/pkgs
                          /Users/user/.conda/pkgs
       envs directories : /Users/user/miniconda/envs
                          /Users/user/.conda/envs
               platform : osx-arm64
             user-agent : conda/25.9.1 requests/2.32.4 CPython/3.13.5 Darwin/24.6.0 OSX/15.6.1 solver/libmamba conda-libmamba-solver/25.4.0 libmambapy/2.0.5 aau/0.7.2
                UID:GID : 501:20
             netrc file : None
           offline mode : False

Conda Config

Conda list

Additional Context

No response