docs(plugin-spec): the Plugin Testing section states only what ships; drop the starter-test clause

The blank starter's note.test.ts is held off this PR, so the sentence
naming it described nothing a scaffolded project carries today.

Claude-Session: https://claude.ai/code/session_01VoSxBQujKLZKPwK2u5ehQ6
Co-authored-by: Claude <noreply@anthropic.com>

Author: claude

content/docs/protocol/kernel/plugin-spec.mdx

@@ -878,9 +878,8 @@ const crm = stack.kernel.getService<CRMService>('crm');
 
 A pure helper with no engine behind it needs no harness: test it with plain
 vitest. Many test files can share one boot through `bootStackOnce(config)`,
-under vitest's `isolate: false`. A project scaffolded with
-`npx create-objectstack` ships one test written this way (`note.test.ts`), and
-the `@objectstack/verify` README documents every method and boot option.
+under vitest's `isolate: false`. The `@objectstack/verify` README documents
+every method and boot option.
 
 ## Plugin Development Workflow