docs: document plugin cli helpers

src/cli/plugins-cli.ts

@@ -1,3 +1,4 @@
+// Commander registration for plugin list/search/inspect/install/update/authoring commands.
 import type { Command } from "commander";
 import { formatDocsLink } from "../../packages/terminal-core/src/links.js";
 import { theme } from "../../packages/terminal-core/src/theme.js";
@@ -52,6 +53,7 @@ export type PluginAuthoringInitOptions = {
 };
 
 function createModuleLoader<T>(load: () => Promise<T>): () => Promise<T> {
+  // Plugin runtime modules are heavy; load each command surface once on first use.
   let promise: Promise<T> | undefined;
   return () => (promise ??= load());
 }