`beet config` groups non-plugin config in the Plugins header if they appear after `plugins`

Minor issue, but with the following beets config:

```yaml
directory: ~/Music/Library
library: ~/Music/beetslibrary.db
paths:
default: $albumartist/$original_year - $album/$track - $title
plugins:
- musicbrainz
```

`beet config` outputs this:
```
directory: ~/Music/Library
# --------------- Main ---------------

library: ~/Music/beetslibrary.db
paths:
default: $albumartist/$original_year - $album/$track - $title

# --------------- Plugins ---------------

plugins: [musicbrainz]
disabled_plugins: []
musicbrainz:
search_limit: 5
data_source_mismatch_penalty: 0.5
search_query_ascii: no
genres: no
genres_tag: genre
external_ids:
discogs: no
bandcamp: no
spotify: no
deezer: no
tidal: no
extra_tags: []
```

makes sense. But with the following config, where `paths` appears *after* `plugins`:
```yaml
directory: ~/Music/Library
library: ~/Music/beetslibrary.db
plugins:
- musicbrainz
paths:
default: $albumartist/$original_year - $album/$track - $title
```

`beet config` outputs this:
```
directory: ~/Music/Library
# --------------- Main ---------------

library: ~/Music/beetslibrary.db

# --------------- Plugins ---------------

plugins: [musicbrainz]
paths:
default: $albumartist/$original_year - $album/$track - $title
disabled_plugins: []
musicbrainz:
search_limit: 5
data_source_mismatch_penalty: 0.5
search_query_ascii: no
genres: no
genres_tag: genre
external_ids:
discogs: no
bandcamp: no
spotify: no
deezer: no
tidal: no
extra_tags: []
```

which is confusing, I couldn't find the `paths` part at first because I was looking at the "Main" config part. I think that this is a bug: it should appear there, regardless of the order of config parts.

### Setup

* OS: Linux Mint 22.3, 6.17.0-23-generic
* Python version: 3.12.3
* beets version: 2.11.0