[DOCS] plugins-reference still shows a flat `agents/` tree and omits recursive scanning and path-scoped identifiers

### Documentation Type

Incorrect/outdated documentation

### Documentation Location

https://code.claude.com/docs/en/plugins-reference

### Section/Topic

"Standard plugin layout" tree and the "Agents" component section

### Current Documentation

The layout tree shows `agents/` as flat top-level files only (verified 2026-09-16):

```text
├── agents/ # Subagent definitions
│ ├── security-reviewer.md
│ ├── performance-tester.md
│ └── compliance-checker.md
```

The "Agents" section says only:

> **Location**: `agents/` directory in plugin root

The page contains no occurrence of "recursive", "subfolder", or "subdirectory" in the context of `agents/`.

### What's Wrong or Missing?

`/en/sub-agents` documents two behaviors that `/en/plugins-reference` does not mention:

> Claude Code scans `.claude/agents/` and `~/.claude/agents/` recursively, so you can organize definitions into subfolders such as `agents/review/` or `agents/research/`.

> Plugin `agents/` directories are also scanned recursively. Unlike project and user scopes, a subfolder inside a plugin's `agents/` directory becomes part of the scoped identifier: a file at `agents/review/security.md` in plugin `my-plugin` registers as `my-plugin:review:security`.

The reference page is the page a plugin author reads to learn the layout. That page shows `agents/` flat, while it shows `skills/` nested. A reader concludes that subfolders under `agents/` are unsupported. The path-scoped identifier rule also changes how a user invokes the agent, and the reference page never states it.

### Suggested Improvement

Two small edits:

1. Add one nested example to the layout tree:

```text
├── agents/ # Subagent definitions (scanned recursively)
│ ├── security-reviewer.md
│ ├── performance-tester.md
│ └── review/
│ └── compliance-checker.md # registers as my-plugin:review:compliance-checker
```

2. Add one paragraph to the "Agents" component section, after the **Location** line:

> Claude Code scans the `agents/` directory recursively. A subfolder becomes part of the scoped identifier: `agents/review/security.md` in plugin `my-plugin` registers as `my-plugin:review:security`. See [Organize subagents in subdirectories](/docs/en/sub-agents) for the project and user scope rules.

### Impact

Medium - Makes feature difficult to understand

### Additional Context

Lineage: #58950 first asked for this clarification and the stale bot closed it. #68046 refiled the remaining plugins-reference gap on 2026-06-12, and the stale bot closed it on 2026-09-14 with no maintainer reply. The bot's closing note asks for a new issue when the topic is still relevant, so this is that issue.

The gap is unchanged since #68046. One maintainer reply that confirms the sub-agents wording is the intended contract resolves this issue.

Open the plugins-reference page and compare its “Standard plugin layout” and “Agents” sections with the referenced sub-agents guidance. Update the tree and Agents section to document recursive scanning and path-scoped identifiers, then verify the page includes the nested example and links to the sub-agents rules.

Written by the indexing model from the issue text.