docs(spec): regenerate the kernel/cli-extension reference page

Regenerated with `pnpm --filter @objectstack/spec gen:docs` after a spec
build; the page lifts the module TSDoc, so only step 2 moves.

Claude-Session: https://claude.ai/code/session_01UtnxvdiN376GF3sgXwAw4d
Co-authored-by: Claude <noreply@anthropic.com>

Author: claude

content/docs/references/kernel/cli-extension.mdx

@@ -17,8 +17,11 @@ built-in plugin system.
 
 1. **Declare** — Plugin's `package.json` includes an `oclif` config section
    declaring its commands directory and any topics.
-2. **Discover** — The main CLI (`@objectstack/cli`) lists the plugin in its
-   `oclif.plugins` array, or users install it via `os plugins install <pkg>`.
+2. **Discover** — oclif loads a plugin that the CLI's own `package.json`
+   lists in both `oclif.plugins` and `dependencies`. `@objectstack/cli`
+   lists none and ships no plugin manager, so `os plugins` is not a
+   command. To add a plugin's commands to `os`, build an `os` distribution:
+   a package whose own `package.json` lists the plugin in both places.
 3. **Load** — oclif automatically discovers and registers all Command classes
    exported from the plugin's commands directory.